;; reproducer for use in emacs -Q:
;; invoke load-file on this file,
;; then follow the interactive steps at the very end.

(emacs-version) ; 29.3
(require 'eglot) ; 1.17.0

;; --- these steps are documented at
;; https://github.com/golang/tools/blob/master/gopls/doc/emacs.md#configuring-project-for-go-modules-in-emacs

(require 'project) ; 0.11.0

(defun project-find-go-module (dir)
  (when-let ((root (locate-dominating-file dir "go.mod")))
    (cons 'go-module root)))

(cl-defmethod project-root ((project (head go-module)))
  (cdr project))

(add-hook 'project-find-functions #'project-find-go-module)
;; -----

; Use your favorite modifier; s is super, aka ⌘ key on Mac.
(global-set-key (kbd "s-<mouse-1>") #'xref-find-definitions-at-mouse)

;; This file comes from github.com/dominikh/go-mode.el@master.
(load-file "~/w/go-mode.el/go-mode.el")

;; Create a new Go buffer.
(with-current-buffer (find-file "/tmp/a.go")
  (eglot-ensure)
  (insert "package main\n\nimport \"fmt\"\n\nfunc main() {\n\tfmt.Println()\n}\n")
  (set-buffer (current-buffer)))

;; You should now be in a Go buffer in go-mode with eglot enabled.
;;
;; Now: position the point in "fmt", and then ⌘-click on "Println".
;; For me, Emacs navigates to the declaration of "fmt", not "Println".
;; The converse is true as well: with the point in Println,
;; a ⌘-click on fmt goes to the declaration of Println.