lsp-mode using shell-file-name for TRAMP connections

[cj-obrien]

Thank you for the bug report

• [X] I am using the latest version of lsp-mode related packages.
• [X] I checked FAQ and Troubleshooting sections
• [X] You may also try reproduce the issue using clean environment using the following command: M-x lsp-start-plain

Bug description

lsp-mode.el uses shell-file-name to launch the language server (clangd, in my case) even when connected to a remote host via TRAMP. I use fish on my local host, but it is not installed on a remote machine I use for development; this prevents me from using lsp-mode unless I first customize shell-file-name.

Surely the TRAMP remote-shell property would be a more appropriate choice?

https://www.gnu.org/software/tramp/#Predefined-connection-information

Steps to reproduce

1. Launch emacs from fish shell
2. Browse remote host via TRAMP
3. Open C source file on remote host
4. Configure project root when prompted
5. Receive notification that clangd process has failed to start
6. Check clangd-tramp::stderr buffer and observe that clangd did not start because /usr/bin/fish was not found.

Expected behavior

The shell specified by the TRAMP remote-shell property for this host is used in place of fish

Which Language Server did you use?

lsp-clangd

OS

Linux

Error callstack

No response

Anything else?

No response

[sprig]

Affected by same issue. The PR fixes it for me