Imenu is missing multi-line golang function signatures

Question

When a golang function signature is split with a linebreak it does not appear in imenu nor helm-imenu. I would like to jump between functions using helm-imenu, but this issue is in my way. Not hard-wrapping the function signatures is not a solution because others on my team have other preferences.

For example:

// This function does _not_ appear in imenu.
func (b *Foo) LongFunction(ctx context.Context, a A,
    b B, c C) foobar.Bazzybaz {
...
}

// But this one does!
func (b *Foo) ShortFunction(ctx context.Context, d D) foobar.Wazoo {
...
}

Short of fixing the problem for me, it would be super helpful if you could point me towards where helm-menu/imenu gets its symbol list in the first place. Or another package suggestion for fuzzy-searching the file's function list.

emacs 24.5 (9.0)
osx 10.12.3

Answer 1

Fixed it by changing the value of imenu-generic-expression to

'(("type" "^[ \t]*type *\\([^ \t\n\r\f]*[ \t]*\\(struct\\|interface\\)\\)" 1)
  ("func" "^func *\\(.*\\)" 1)))

Which has two advantages over the original value. it recognizes split-line functions, and it notices embedded types.

I'll probably submit a PR to go-mode, but until then to get this rolling you can do

;;; Go mode.
(defun my-go-mode-hook ()
  ; Custom imenu regexes
  (setq imenu-generic-expression
        '(("type" "^[ \t]*type *\\([^ \t\n\r\f]*[ \t]*\\(struct\\|interface\\)\\)" 1)
          ("func" "^func *\\(.*\\)" 1)))
  )

 (add-hook 'go-mode-hook 'my-go-mode-hook)

Thanks for the tip about imenu-generic-expression Drew!