Can I use emacs with company-mode and company-go to complete Go's standard library function names?

Question

Below is my emacs init file that relates to Go. I'm trying to use company mode to auto completes Go.

;;===================================================
; Golang related configuration
;;===================================================
(defun my-go-mode-hook ()
  ; Add go-guru
  (require 'go-guru)

  (require 'company)
  (require 'company-go)

  ; Use goimports instead of go-fmt
  (setq gofmt-command "goimports")
  ; Call Gofmt before saving
  (add-hook 'before-save-hook 'gofmt-before-save)
  ; Customize compile command to run go build
  (if (not (string-match "go" compile-command))
      (set (make-local-variable 'compile-command)
           ;"go build -v && go test -v && go vet"))
           "go run"))
  ; Godef jump key binding
  (local-set-key (kbd "M-.") 'godef-jump))
(add-hook 'go-mode-hook 'my-go-mode-hook)
; Highlight identifiers in Golang by default
(add-hook 'go-mode-hook #'go-guru-hl-identifier-mode)

However, it seems that the company mode can only completes words that have been used in the buffer. See below screen shot.

What I want is to complete Go's builtin functions, like fmt.Fprintln. It seems company mode can't do that. See below screen shot.

I want to confirm, is it true? Can emacs auto completes Go's builtin functions? Are there any example emacs init files that I can use as a reference? Thanks in advance.

---

Update

Confirmed I installed gocode.

I've cleared my init.el and only contains the minimal code to do the completion, but it still not work (emacs restarted).

---

Update2

Yes gocode is running.

Answer 1

You need to tell company-mode what backend to use. In my init file I have the following code

(add-hook 'go-mode-hook
      (lambda ()
        (set (make-local-variable 'company-backends) '(company-go))
        (company-mode)))

You will also need the gocode autocomplete daemon which you can get by executing go get github.com/nsf/gocode.