Fix lazy loading of elisp-mode config

elisp-mode is loaded at startup, so the usual methods won't work.
Instead, we tie a transient advice to the emacs-lisp-mode
function, *however*, this function is commonly called by various
packages to parse elisp code! So we have to make sure the emacs lisp
module only initializes the first time it is used interactively.

modules/lang/emacs-lisp/config.el

@@ -2,7 +2,21 @@
 
 (add-to-list 'auto-mode-alist '("\\.Cask\\'" . emacs-lisp-mode))
 
-(defun +emacs-lisp|init ()
+(add-hook! 'emacs-lisp-mode-hook
+  #'(;; 3rd-party functionality
+     auto-compile-on-save-mode doom|enable-delete-trailing-whitespace
+     ;; fontification
+     rainbow-delimiters-mode highlight-quoted-mode highlight-numbers-mode +emacs-lisp|extra-fontification
+     ;; initialization
+     +emacs-lisp|init-imenu +emacs-lisp|disable-flycheck-maybe))
+
+(defun +emacs-lisp|init (&rest _)
+  ;; Some plugins will run `emacs-lisp-mode' with `emacs-lisp-mode-hook' set to
+  ;; nil (cough yasnippet cough) or its mode hooks delayed. This prematurely
+  ;; fires this function. Most of these setters affect emacs-lisp-mode-hook, so
+  ;; they'd be swallowed up if it's letbound to nil, causing a half-initialized
+  ;; elisp-mode in some sessions.
+  (when (and emacs-lisp-mode-hook (not delay-mode-hooks))
     (set-repl-handler! 'emacs-lisp-mode #'+emacs-lisp/repl)
     (set-eval-handler! 'emacs-lisp-mode #'+emacs-lisp-eval)
     (set-lookup-handlers! 'emacs-lisp-mode :documentation 'info-lookup-symbol)
@@ -16,17 +30,11 @@
                  ("advice-add" "advice-remove")
                  ("add-hook" "remove-hook")
                  ("add-hook!" "remove-hook!")))
-
-  (add-hook! 'emacs-lisp-mode-hook
-    #'(;; 3rd-party functionality
-       auto-compile-on-save-mode doom|enable-delete-trailing-whitespace
-       ;; fontification
-       rainbow-delimiters-mode highlight-quoted-mode highlight-numbers-mode +emacs-lisp|extra-fontification
-       ;; initialization
-       +emacs-lisp|init-imenu +emacs-lisp|disable-flycheck-maybe))
-
     ;;
-  (defun +emacs-lisp|extra-fontification ()
+    (advice-remove #'emacs-lisp-mode #'+emacs-lisp|init)))
+(advice-add #'emacs-lisp-mode :before #'+emacs-lisp|init)
+
+(defun +emacs-lisp|extra-fontification ()
   "Display lambda as a smybol and fontify doom module functions."
   (font-lock-add-keywords
    nil `(;; Highlight custom Doom cookies
@@ -34,7 +42,7 @@
          ;; Highlight doom/module functions
          ("\\(^\\|\\s-\\|,\\)(\\(\\(doom\\|\\+\\)[^) ]+\\|[^) ]+!\\)[) \n]" (2 font-lock-keyword-face)))))
 
-  (defun +emacs-lisp|init-imenu ()
+(defun +emacs-lisp|init-imenu ()
   "Improve imenu support with better expression regexps and Doom-specific forms."
   (setq imenu-generic-expression
         '(("Evil Commands" "^\\s-*(evil-define-\\(?:command\\|operator\\|motion\\) +\\(\\_<[^ ()\n]+\\_>\\)" 1)
@@ -53,15 +61,13 @@
           ("Variables" "^\\s-*(defvar\\(?:-local\\)?\\s-+\\(\\(?:\\sw\\|\\s_\\|\\\\.\\)+\\)[[:space:]\n]+[^)]" 1)
           ("Types" "^\\s-*(\\(cl-def\\(?:struct\\|type\\)\\|def\\(?:class\\|face\\|group\\|ine-\\(?:condition\\|error\\|widget\\)\\|package\\|struct\\|t\\(?:\\(?:hem\\|yp\\)e\\)\\)\\)\\s-+'?\\(\\(?:\\sw\\|\\s_\\|\\\\.\\)+\\)" 2))))
 
-  (defun +emacs-lisp|disable-flycheck-maybe ()
+(defun +emacs-lisp|disable-flycheck-maybe ()
   "Disable flycheck-mode if in emacs.d."
   (when (or (not buffer-file-name)
             (cl-loop for dir in (list doom-emacs-dir doom-private-dir)
                      if (file-in-directory-p buffer-file-name dir)
                      return t))
-      (flycheck-mode -1))))
-
-(add-transient-hook! 'emacs-lisp-mode (+emacs-lisp|init))
+    (flycheck-mode -1)))
 
 
 ;;