dump: auto-dump emacs on load if layer list has changed

* rename core-dump.el to core-dumper.el
* add function spacemacs/dump-emacs
* explicitly load core-dumper.el file in init.el
* asynchronously dump emacs if layer list has changed, see special buffer
  *spacemacs-dumper* for the output.

core/core-configuration-layer.el

@@ -554,8 +554,11 @@ refreshed during the current session."
 To prevent package from being installed or uninstalled set the variable
 `spacemacs-sync-packages' to nil."
   (run-hooks 'configuration-layer-pre-load-hook)
-  (dotspacemacs|call-func dotspacemacs/layers "Calling dotfile layers...")
-  (spacemacs|when-dumping
+  (setq changedp nil)
+  (let ((layers dotspacemacs-configuration-layers))
+    (dotspacemacs|call-func dotspacemacs/layers "Calling dotfile layers...")
+    (setq changedp (not (equal layers dotspacemacs-configuration-layers))))
+  (when changedp
     (setq dotspacemacs--configuration-layers-saved
           dotspacemacs-configuration-layers)
     (when (spacemacs-buffer//choose-banner)
@@ -605,7 +608,8 @@ To prevent package from being installed or uninstalled set the variable
     (configuration-layer//configure-packages configuration-layer--used-packages)
     (configuration-layer//load-layers-files configuration-layer--used-layers
                           '("keybindings.el"))
-    (dotspacemacs|call-func dotspacemacs/user-load "Calling dotfile user-load..."))
+    (dotspacemacs|call-func dotspacemacs/user-load "Calling dotfile user-load...")
+    (spacemacs|unless-dumping (spacemacs/dump-emacs)))
   (run-hooks 'configuration-layer-post-load-hook))
 
 (defun configuration-layer/load-auto-layer-file ()

core/core-dumper.el

@@ -1,4 +1,4 @@
-;;; core-dump.el --- Spacemacs Core File
+;;; core-dumper.el --- Spacemacs Core File
 ;;
 ;; Copyright (c) 2012-2018 Sylvain Benner & Contributors
 ;;
@@ -45,6 +45,14 @@ You should not used this function, it is reserved for some specific process."
   `(unless (eq 'dumping spacemacs-dump-mode)
      ,@body))
 
+(defun spacemacs/dump-emacs ()
+  "Dump emacs in a subprocess."
+  (let ((default-directory "~/dev/emacs/src"))
+    (make-process
+     :name "spacemacs-dump"
+     :buffer "*spacemacs-dumper*"
+     :command (list "~/dev/emacs/src/emacs" "--batch" "-l" "~/.emacs.d/dump-init.el" "-eval" "(dump-emacs-portable \"spacedump.pdmp\")"))))
+
 ;; ;; Brute-force load all .el files in ELPA packages
 ;; (dolist (d (directory-files package-user-dir t nil 'nosort))
 ;;   (unless (or (string-equal ".." (substring d -2))
@@ -56,4 +64,4 @@ You should not used this function, it is reserved for some specific process."
 ;;         (message "%s" f)
 ;;         (ignore-errors (load f t))))))
 
-(provide 'core-dump)
+(provide 'core-dumper)

core/core-spacemacs.el

@@ -11,7 +11,6 @@
 (setq message-log-max 16384)
 
 (require 'subr-x nil 'noerror)
-(require 'core-dump)
 (require 'core-emacs-backports)
 (require 'page-break-lines)
 (require 'core-debug)

init.el

@@ -20,6 +20,7 @@
                    "core/core-versions.el"))
 (load-file (concat (file-name-directory load-file-name)
                    "core/core-load-paths.el"))
+(load-file (concat spacemacs-core-directory "core-dumper.el"))
 
 (if (not (version<= spacemacs-emacs-min-version emacs-version))
     (error (concat "Your version of Emacs (%s) is too old. "