emacs: added an early-init.el file

This file will be used by GNU Emacs 27 and later and it be loaded way before
init.el kicks in.

Signed-off-by: Miquel Sabaté Solà <msabate@suse.com>

3 files changed, 83 insertions, 21 deletions

diff --git a/.emacs.d/custom.el b/.emacs.d/custom.el
index ce2962d..53e00bd 100644
--- a/.emacs.d/custom.el
+++ b/.emacs.d/custom.el
@@ -13,7 +13,7 @@
  '(magit-log-arguments '("--graph" "--color" "--decorate" "-n256"))
  '(markdown-command "/usr/bin/markdown-calibre")
  '(package-selected-packages
-   '(js-mode let-alist doom-modeline evil-collection highlight-numbers langtool clang-format+ keycast gif-screencast py-autopep8 elpy inf-ruby move-text git-timemachine debbugs async-await request emojify auctex diminish bats-mode bool-flip salt-mode flycheck-rust rust-playground rust-mode vue-mode coffee-mode json-reformat erc-hl-nicks emoji-cheat-sheet-plus helm-circe htmlize cmake-mode websocket markdown-mode go-mode magit evil-leader evil helm projectile org-eldoc evil-commentary yasnippet yaml-mode which-key web-mode wc-mode use-package terraform-mode smart-tabs-mode slim-mode scss-mode rainbow-delimiters php-mode org-evil olivetti mu4e-alert mmm-jinja2 markdown-preview-mode helm-projectile helm-ag go-eldoc go-add-tags flycheck evil-surround evil-org evil-numbers evil-magit evil-args dockerfile-mode disable-mouse default-text-scale crux cmake-font-lock ag)))
+   '(all-the-icons js-mode let-alist doom-modeline evil-collection highlight-numbers langtool clang-format+ keycast gif-screencast py-autopep8 elpy inf-ruby move-text git-timemachine debbugs async-await request emojify auctex diminish bats-mode bool-flip salt-mode flycheck-rust rust-playground rust-mode vue-mode coffee-mode json-reformat erc-hl-nicks emoji-cheat-sheet-plus helm-circe htmlize cmake-mode websocket markdown-mode go-mode magit evil-leader evil helm projectile org-eldoc evil-commentary yasnippet yaml-mode which-key web-mode wc-mode use-package terraform-mode smart-tabs-mode slim-mode scss-mode rainbow-delimiters php-mode org-evil olivetti mu4e-alert mmm-jinja2 markdown-preview-mode helm-projectile helm-ag go-eldoc go-add-tags flycheck evil-surround evil-org evil-numbers evil-magit evil-args dockerfile-mode disable-mouse default-text-scale crux cmake-font-lock ag)))
 (custom-set-faces
  ;; custom-set-faces was added by Custom.
  ;; If you edit it by hand, you could mess it up, so be careful.
diff --git a/.emacs.d/early-init.el b/.emacs.d/early-init.el
new file mode 100644
index 0000000..5c71a0e
--- /dev/null
+++ b/.emacs.d/early-init.el
@@ -0,0 +1,60 @@
+;;; early-init.el --- early initialization -*- lexical-binding: t; -*-
+;;
+;; Copyright (C) 2020 Miquel Sabaté Solà <mikisabate@gmail.com>
+;;
+;; Author: Miquel Sabaté Solà <mikisabate@gmail.com>
+;; Version: 0.1
+;; Package-Requires: ((emacs "27.0"))
+;; Keywords: convenience, extensions, files, frames, mail, matching, terminals, tools, vc, wp
+;; URL: https://github.com/mssola/dotfiles
+;;
+;; This file is not part of GNU Emacs.
+;;
+;; This program is free software: you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation, either version 3 of the License, or
+;; (at your option) any later version.
+;;
+;; This program is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;; GNU General Public License for more details.
+;;
+;; You should have received a copy of the GNU General Public License
+;; along with this program.  If not, see <http://www.gnu.org/licenses/>.
+;;
+;;; Commentary:
+;;
+;; early-init.el support was added in GNU Emacs 27.x, and it will be loaded before init.el and
+;; before many other elements which are relevant for GNU Emacs. Thus, we should be very cautious as
+;; to what we put in here.
+
+;;; Code:
+
+(defconst mssola-initial-gc-cons-threshold gc-cons-threshold
+  "Initial value of `gc-cons-threshold' at start-up time.")
+
+(defconst mssola-initial-gc-cons-percentage gc-cons-percentage
+  "Initial value of `gc-cons-percentage' at start-up time.")
+
+;; Completely disable the GC by having a ginormous threshold. Bringing this back to its previous
+;; values will be handled by init.el.
+(setq gc-cons-threshold most-positive-fixnum
+      gc-cons-percentage 0.6)
+
+;; Prevent the glimpse of un-styled Emacs by setting these early. Taken from doom-emacs.
+(add-to-list 'default-frame-alist '(tool-bar-lines . 0))
+(add-to-list 'default-frame-alist '(menu-bar-lines . 0))
+(add-to-list 'default-frame-alist '(vertical-scroll-bars))
+
+;; Package initialization.
+(require 'package)
+
+(setq package-archives '())
+(add-to-list 'package-archives '("melpa" . "http://melpa.milkbox.net/packages/") t)
+(add-to-list 'package-archives '("melpa-stable" . "https://stable.melpa.org/packages/") t)
+(add-to-list 'package-archives '("gnu" . "https://elpa.gnu.org/packages/") t)
+(add-to-list 'package-archives '("org" . "https://orgmode.org/elpa/") t)
+
+
+;;; early-init.el ends here
diff --git a/.emacs.d/init.org b/.emacs.d/init.org
index 2612c9e..db15e23 100644
--- a/.emacs.d/init.org
+++ b/.emacs.d/init.org
@@ -44,7 +44,7 @@ git update-index --assume-unchanged emacs/init.el
 From now on our code will be tangled, meaning that it will go into the final =init.el= file. For starters, let's have a good header:
 
 #+BEGIN_SRC elisp
-;;; init.el -*- lexical-binding: t; -*-
+;;; init.el --- init file -*- lexical-binding: t; -*-
 ;;
 ;; Copyright (C) 2016-2020 Miquel Sabaté Solà <mikisabate@gmail.com>
 ;;
@@ -135,21 +135,23 @@ Check the operating system:
   (error "This configuration has been checked only on GNU/Linux and MacOS"))
 #+END_SRC
 
-Temporarily reduce garbage collection so startup time is lower. Idea taken from
-[[https://github.com/purcell][@purcell]].
+Temporarily reduce garbage collection so startup time is lower. Idea taken from [[https://github.com/purcell][@purcell]] and later refined by looking at [[https://github.com/hlissner/doom-emacs][doom-emacs]]. Note that this is handled in the =early-init.el= file for GNU Emacs 27 and later:
 
 #+BEGIN_SRC elisp
-(defconst mssola-initial-gc-cons-threshold gc-cons-threshold
-  "Initial value of `gc-cons-threshold' at start-up time.")
+(unless EMACS-27-OR-LATER
+  (defconst mssola-initial-gc-cons-threshold gc-cons-threshold
+    "Initial value of `gc-cons-threshold' at start-up time.")
 
-(defconst mssola-initial-gc-cons-percentage gc-cons-percentage
-  "Initial value of `gc-cons-percentage' at start-up time.")
+  (defconst mssola-initial-gc-cons-percentage gc-cons-percentage
+    "Initial value of `gc-cons-percentage' at start-up time.")
 
-;; Completely disable the GC by having a ginormous threshold.
-(setq gc-cons-threshold most-positive-fixnum
-      gc-cons-percentage 0.6)
+  ;; Completely disable the GC by having a ginormous threshold.
+  (setq gc-cons-threshold most-positive-fixnum
+        gc-cons-percentage 0.6))
 
-;; Enable the GC back again to its
+;; Enable the GC back again to its previous values. This should also be set here
+;; for GNU Emacs 27 and later because the early-init.el purposely does not
+;; fiddle with this hook.
 (add-hook 'after-init-hook
           (lambda ()
             (setq gc-cons-threshold mssola-initial-gc-cons-threshold
@@ -180,18 +182,18 @@ Compile the =g.el= script and bind it to @@html:<kbd>M-g</kbd>@@.
 Initialize package.
 
 #+BEGIN_SRC elisp
-(require 'package)
+;; In GNU Emacs 27 and later this is handled through the early-init.el file.
+(unless EMACS-27-OR-LATER
+  (require 'package)
 
-(when (version= "26.2" emacs-version)
-  (setq gnutls-algorithm-priority "NORMAL:-VERS-TLS1.3"))
+  (when (version= "26.2" emacs-version)
+    (setq gnutls-algorithm-priority "NORMAL:-VERS-TLS1.3"))
 
-(add-to-list 'package-archives
-             '("melpa" . "http://melpa.milkbox.net/packages/") t)
-(add-to-list 'package-archives
-             '("melpa-stable" . "https://stable.melpa.org/packages/") t)
+  (add-to-list 'package-archives
+               '("melpa" . "http://melpa.milkbox.net/packages/") t)
+  (add-to-list 'package-archives
+               '("melpa-stable" . "https://stable.melpa.org/packages/") t)
 
-;; This is no longer needed as of GNU Emacs 27.x.
-(unless EMACS-27-OR-LATER
   (package-initialize))
 #+END_SRC