Use-package doesn't find autoload

Question

I expect the package to be require'd as soon as mdi-insert is called but I get:

Error (use-package): spaceline :config: Symbol’s function definition is void: mdi-insert

~/.emacs.d/init.el

(let ((default-directory (expand-file-name "lisp/" user-emacs-directory)))
  (normal-top-level-add-subdirs-to-load-path))

(require 'package)
(setq-default
 load-prefer-newer t
 package-enable-at-startup nil)
(add-to-list 'package-archives '("melpa" . "http://melpa.org/packages/") t)
(add-to-list 'package-archives '("org" . "http://orgmode.org/elpa/") t)
(package-initialize)

(unless (package-installed-p 'use-package)
  (package-refresh-contents)
  (package-install 'use-package t))
(setq-default
 use-package-always-defer t
 use-package-always-ensure t)

(use-package org
  :pin org
  :ensure org-plus-contrib)

(use-package spaceline
  :ensure nil
  :demand t
  :config
  (message (mdi-insert "star")))

(use-package mdi :ensure nil)

~/.emacs.d/lisp/mdi/mdi.el: https://github.com/angrybacon/mdi/blob/master/mdi.el#L1952-L1957

(mdi is a package I wrote myself and placed under lisp/)

Also, it works with :demand t in the declaration for mdi. But I would like to defer the package if possible.

Answer 1

Maybe I am missing something, but the linked mdi.el file does not define the function mdi-insert. Its main entry-point is the autoloaded function mdi.

Either way, if adding :demand t to the mdi use-package form results in the desired behaviour, this means that the definitions in mdi.el being used aren't being successfully autoloaded. Note that adding an autoload cookie (;;;###autoload) to an Elisp file does not automatically make it visible to Emacs. See the Elisp Manual and this post by lunaryorn for more information.

Some other observations:

• If you intend to byte-compile your user-init-file, especially in a noninteractive emacs, you may want to eval-and-compile modifications to load-path (in your case, the call to normal-top-level-add-subdirs-to-load-path).
• The use-package form for the spaceline package includes the :demand t clause. This means that the package will be required immediately, so everything in its :config clause should either be previously defined or autoloaded.
• Given my previous observation that mdi.el does not seem to define the function mdi-insert, I find it strange that adding :demand t to the mdi use-package form results in the desired behaviour. Again, I could be missing something, though.

Answer 2

(use-package mdi :ensure nil)

is mdi installed?

You might also have to add

:after mdi

in use-package spaceline