Cannot set tab-width in Golang mode with Spacemacs

Question

I set the tab-width for Golang to 2 using the following:

(add-hook 'go-mode-hook
          (lambda ()
            (setq-default indent-tabs-mode 1)
            (setq-default tab-width 2)))

And when I check the tab-width variable, it shows:

   tab-width is a variable defined in ‘C source code’.
    Its value is 8
    Local in buffer plugin.go; global value is 2

      Automatically becomes buffer-local when set.
      This variable is safe as a file local variable if its value
      satisfies the predicate ‘integerp’.

But when I open any .go file, the tab width is still 8. Why?

Answer 1

The docs tell you to configure the go-tab-width spacemacs layer variable.

In .spacemacs, inside dotspacemacs/layers is a variable called dotspacemacs-configuration-layers. Add the go layer variables like so:

(defun dotspacemacs/layers ()
  (setq-default
   dotspacemacs-configuration-layers
   '(
     (go :variables go-tab-width 2)
   )))

Answer 2

setq-default sets the global value, whereas you want to set the value in your particular go-mode buffer. Basically, using setq-default within a mode-hook is never right. Try:

(add-hook 'go-mode-hook
          (lambda ()
            (setq indent-tabs-mode 1)
            (setq tab-width 2)))