core: async import of env.vars and add new dotfile variable

* new variable dotspacemacs-import-env-vars-from-shell
 * asynchronous import of environments variables
 * move loadenv function to funcs.el
 * update documentation

core/core-dotspacemacs.el

@@ -55,6 +55,13 @@ exists. Otherwise, fallback to ~/.spacemacs"))
 `+distributions'. For now available distributions are `spacemacs-base'
 or `spacemacs'.")
 
+(defvar dotspacemacs-import-env-vars-from-shell (and (display-graphic-p)
+                                           (or (eq system-type 'darwin)
+                                               (eq window-system 'x)))
+  "If non-nil then Spacemacs will import your PATH and environment variables
+from your default shell on startup. This is enabled by default for macOS users
+and X11 users.")
+
 (defvar dotspacemacs-enable-emacs-pdumper nil
   "If non-nil then enable support for the portable dumper. You'll need
 to compile Emacs 27 from source following the instructions in file

core/templates/.spacemacs.template

@@ -155,6 +155,13 @@ It should only modify the values of Spacemacs settings."
    ;; If non-nil output loading progress in `*Messages*' buffer. (default nil)
    dotspacemacs-verbose-loading nil
 
+   ;; If non-nil then Spacemacs will import your PATH and environment variables
+   ;; from your default shell on startup. This is enabled by default for macOS
+   ;; users and X11 users.
+   dotspacemacs-import-env-vars-from-shell (and (display-graphic-p)
+                                                (or (eq system-type 'darwin)
+                                                    (eq window-system 'x)))
+
    ;; Specify the startup banner. Default value is `official', it displays
    ;; the official spacemacs logo. An integer value is the index of text
    ;; banner, `random' chooses a random text banner in `core/banners'

doc/DOCUMENTATION.org

@@ -1718,22 +1718,28 @@ There are also some handy globally available key bindings related to workspaces:
 | ~SPC b W~   | go to workspace and window by buffer |
 
 * Environment variables and PATH from the shell
-When using the Emacs GUI environment variables defined by your shell may not
-be available to the Emacs process. This is especially true for macOS.
+To import your environment variable and =PATH= at startup set the variable
+=dotspacemacs-import-env-vars-from-shell=  to non-nil.
 
-The command to fetch the environment variables from your shell is very expensive
-and increases the startup time quite a lot.
+This should be necessary only to macOS users and X11 users using the GNU
+build of Emacs.
 
-For this reason, Spacemacs caches the PATH value and some environment variables
-in the file located at =~/.emacs.d/.cache/.env-vars=.
+#+BEGIN_EXAMPLE emacs-lisp
+(setq-default  dotspacemacs-import-env-vars-from-shell (and (display-graphic-p)
+                                                (or (eq system-type 'darwin)
+                                                    (eq window-system 'x))))
+#+END_EXAMPLE
 
-Any environment variables that are not found are still written to the cache file
-with the value =<VAR>-NOTFOUND-PLEASE-DEFINE-IN-YOUR-SHELL=.
+At anytime you can import the environment variables by calling the function
+=spacemacs/loadenv=.
 
-Spacemacs won't update the cached values by itself, if you want to update your
-shell variables then either delete the cache file or execute the interactive
-function =spacemacs/import-path= and restart Emacs to fetch any updated
-environment variables.
+You can define a different shell than the default shell by setting the variable
+=shell-file-name= in the =dotspacemacs/user-init= function of your dotfile.
+
+#+BEGIN_EXAMPLE emacs-lisp
+(defun dotspacemacs/user-init ()
+  (setq shell-file-name "/usr/local/bin/fish"))
+#+END_EXAMPLE
 
 * Commands
 ** Vim key bindings

layers/+distributions/spacemacs-bootstrap/funcs.el

@@ -11,6 +11,29 @@
 
 
 
+(defun spacemacs/loadenv ()
+  "Gets and sets all the environment variables from user shell."
+  (interactive)
+  (spacemacs-buffer/message "Importing environment variables..")
+  (require 'async nil t)
+  (async-start
+   `(lambda ()
+     ,(async-inject-variables "\\`shell-file-name\\'")
+     (split-string (shell-command-to-string "env") "\n"))
+   (lambda (envvars)
+     (spacemacs-buffer/message "Imported environment variables:")
+     (dolist (env envvars)
+       (if (string-match "^[a-zA-Z_]+[a-zA-Z0-9_]*=" env)
+           (let* ((var (split-string env "="))
+                  (k (car var))
+                  (v (cadr var)))
+             (spacemacs-buffer/message "  - %s=%s" k v)
+             (if (string-equal "PATH" k)
+                 (setq exec-path (split-string v path-separator))
+               (setenv k v))))))))
+
+
+
 (defun spacemacs/state-color-face (state)
   "Return the symbol of the face for the given STATE."
   (intern (format "spacemacs-%s-face" (symbol-name state))))

layers/+distributions/spacemacs-bootstrap/local/spacemacs-environment/spacemacs-environment.el

@@ -1,12 +0,0 @@
-(defun spacemacs//loadenv ()
-  "Gets and sets all the environment variables from a terminal instance."
-  (interactive)
-  (let ((envvars (split-string (shell-command-to-string "env") "\n")))
-    (dolist (env envvars)
-      (if (string-match "^[a-zA-Z_]+[a-zA-Z0-9_]*=" env)
-          (let* ((var (split-string env "="))
-                 (k (car var))
-                 (v (cadr var)))
-            (setenv k v))))))
-
-(provide 'spacemacs-environment)

layers/+distributions/spacemacs-bootstrap/packages.el

@@ -18,11 +18,7 @@
         (bind-key :step bootstrap)
         (diminish :step bootstrap)
         (evil :step bootstrap)
-        (spacemacs-environment :step bootstrap
-                               :location local
-                               :toggle (or (spacemacs/system-is-mac)
-                                           (spacemacs/system-is-linux)
-                                           (eq window-system 'x)))
+        (spacemacs-environment :step bootstrap :location built-in)
         (hydra :step bootstrap)
         (use-package :step bootstrap)
         (which-key :step bootstrap)
@@ -498,8 +494,8 @@
   (spacemacs|diminish which-key-mode " Ⓚ" " K"))
 
 (defun spacemacs-bootstrap/init-spacemacs-environment ()
-  (require 'spacemacs-environment)
-  (spacemacs//loadenv))
+  (when dotspacemacs-import-env-vars-from-shell
+    (spacemacs/loadenv)))
 
 ;; pre packages