Possibly wrong path for fsautocomplete

[arialdomartini]

Description

eglot-fsharp--path-to-server expects fsautocomplete to be in netcore subdir. dotnet tool install does not install it in that subdir.

Repro steps

• Install fsautocomplete with

dotnet tool install --global fsautocomplete --version 0.72.3

as recommended in https://www.nuget.org/packages/fsautocomplete.

• Notice how fsautocomplete is being installed in ~/.dotnet/tools, not in ~/.dotnet/tools/netcore.
• Use fsharp-mode and eglot-fsharp

Actual behavior

I get the error:

Error in post-command-hook (#[0 "\303\301!\205�\0r\301q\210\304\305\300\242\306#\210
?\205�\0\307\310\311 \")\207" [(#0) #<buffer Program.fs> eglot--managed-mode buffer-live-p remove-hook post-command-hook t apply eglot--connect eglot--guess-contact] 4]): (file-missing "Doing vfork" "No such file or directory")

Known workarounds

I think the problem is with the function:

(defun eglot-fsharp--path-to-server ()
    "Return FsAutoComplete path."
    (file-truename (concat eglot-fsharp-server-install-dir "netcore/fsautocomplete" (if (eq system-type 'windows-nt) ".exe" ""))))

which uses the hardcoded value netcore/fsautocomplete.

With the help of @protesilaos I modified it to:

(defun eglot-fsharp--path-to-server ()
    "Return FsAutoComplete path."
    (file-truename (concat eglot-fsharp-server-install-dir "fsautocomplete" (if (eq system-type 'windows-nt) ".exe" ""))))

which fixed the problem.
I work on Arch Linux with SDK 8. I am not sure if this path is also valid for other configurations. It would probably a good idea to have that value parametric.

Related information

• Operating system
  Linux version 6.8.9-arch1-1

• Emacs version
  GNU Emacs 30.0.50 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.24.38, cairo version 1.18.0) of 2023-10-23

• .NET Runtime, CoreCLR or Mono Version
  8.0.104

[arialdomartini]

I just found out that the problem arises only if fsautocomplete has being installed via dotnet tool.

The ambiguity could be because dotnet tool and eglot-fsharp install fsautocomplete in 2 different paths:

Tool	Install path
dotnet tool	~/.dotnet/tools
eglot-fsharp	~/.dotnet/tools/netcore

[arialdomartini]

I think I found the problem.
I had this configuration in place:

(use-package eglot-fsharp
  :ensure t
  :after fsharp-mode
  :config
  (setq eglot-fsharp-server-install-dir "~/.dotnet/tools/"))

because I wanted to make sure that fsautocomplete was not downloaded twice. I learnt that by default eglot-fsharp does not downlod fsautocomplete in ~/.dotnet, but in the startard XDG directory.

My suggestion would be to include the hardcoded netcore path in eglot-fsharp-server-install-dir so in case a user configures it, as above, netcore is not added, with something like:

(defcustom eglot-fsharp-server-install-dir
  (concat (locate-user-emacs-file "FsAutoComplete") "/" "netcore")
  "Install directory for FsAutoComplete."
  :group 'eglot-fsharp
  :risky t
  :type 'directory)

With this,

[juergenhoetzel]

Fixed in #342

(use-package eglot-fsharp
  :ensure t
  :after fsharp-mode
  :custom (eglot-fsharp-server-install-dir nil))

will use the global user tool path.

[arialdomartini]

Works like a breeze! Thank you.