xref--process-file-region takes shell-file-name, that should depend on
the remote system.  I could use something like

   (with-parsed-tramp-file-name default-directory d
     (tramp-get-method-parameter d 'tramp-remote-shell))

but it seems that `with-parsed-tramp-file-name' is not used outside of
tramp, and byte-compiling triggers a warning.  Is there some better way
to do this?
  
> To get you started, here's one example of this feature's usage:
> https://github.com/company-mode/company-mode/blob/c25f1fbc3850e36e6521b77fa1641d5583365d8b/company-gtags.el#L71-L96
>
> And you can search in Emacs's own repository, of course, for other examples.

-- 
	Philip Kaludercic