Eglot should use `shell-file-name` when launching the server for a remote file

[jeberger]

Steps to reproduce:

• On the remote machine:
  • Install a language server in a non-standard path (e.g. rust-analyzer, which installs in a subdirectory under $HOME and not /usr/bin)
  • Make sure that the server is in the path for a shell other than sh (e.g. set the path in .zprofile for zsh).
• On the local machine:
  • Open a file remotely through TRAMP
  • Set shell-file-name to the shell you're using on the remote (e.g. (setq shell-file-name "zsh"))
  • M-x `eglot`.

Expected result:

Eglot should start

Actual result:

Eglot asks Enter program to execute (or <host>:<port>):, then when I type rust-analyzer it fails with message [jsonrpc] Server exited with status 127. Looking at eglot-events-buffer, it is clear that eglot tried to use sh to start the server.

Partial fix

The server starts correctly if I change function eglot--cmd to use (or shell-file-name "sh") instead of plain "sh", e.g.:

(defun eglot--cmd (contact)
  "Helper for `eglot--connect'."
  (if (file-remote-p default-directory)
      ;; TODO: this seems like a bug, although it’s everywhere. For
      ;; some reason, for remote connections only, over a pipe, we
      ;; need to turn off line buffering on the tty.
      ;;
      ;; Not only does this seem like there should be a better way,
      ;; but it almost certainly doesn’t work on non-unix systems.
      (list (or shell-file-name "sh") "-c"
            (string-join (cons "stty raw > /dev/null;"
                               (mapcar #'shell-quote-argument contact))
                         " "))
    contact))

It still fails to autodetect the server and asks for the program to execute though.

[joaotavora]

Please report this to the Emacs bug tracker with M-x report-emacs-bug and put Michael Albinus and me in CC: or X-Debbugs-CC:. I have very little TRAMP experience.

[jeberger]

Please report this to the Emacs bug tracker with M-x report-emacs-bug and put Michael Albinus and me in CC: or X-Debbugs-CC:. I have very little TRAMP experience.

Done: https://debbugs.gnu.org/cgi/bugreport.cgi?bug=61748 but I couldn't put you or Michael Albinus in CC since I don't have your email addresses.

[joaotavora]

Closing. Let's continue in that bug. I've also reproduced the problem in the meantime, and it's indeed a bit annoying.