Drop Emacs 26.x support

Emacs 27.x has been the stable version of Emacs for nearly a year, and
introduces a litany of bugfixes, performance, and quality-of-life
improvements that significantly reduce Doom's maintenance burden (like
XDG support, early-init.el, image manipulation without imagemagick, a
native JSON library, harfbuzz support, pdumper, and others).

With so many big changes on Doom's horizon, I like having one less (big)
thing to worry about.

Also reverts bb677cf7a (#5232) as it is no longer needed.

core/autoload/themes.el

@@ -40,9 +40,7 @@ all themes. It will apply to all themes once they are loaded."
        (when (or (get 'doom-theme 'previous-themes)
                  (null doom-theme))
          (funcall #',fn))
-       ;; TODO Append to `doom-load-theme-hook' with DEPTH instead when Emacs
-       ;;      26.x support is dropped.
-       (add-hook 'doom-customize-theme-hook #',fn 'append))))
+       (add-hook 'doom-customize-theme-hook #',fn 100))))
 
 ;;;###autoload
 (defmacro custom-set-faces! (&rest specs)

core/cli/doctor.el

@@ -54,11 +54,9 @@ in."
      (warn! "Emacs %s detected" emacs-version)
      (explain! "Doom supports this version, but you are living on the edge! "
                "Be prepared for breakages in future versions of Emacs."))
-    ((= emacs-major-version 26)
-     (warn! "Emacs %s detected" emacs-version)
-     (explain! "Doom is dropping Emacs 26.x support in June 2021. Consider "
-               "upgrading to Emacs 27.1 (or better: 27.2) soon!"
-               emacs-version))))
+    ((< emacs-major-version 27)
+     (error! "Emacs %s detected, Doom only supports 27.1 and newer"
+             emacs-version))))
 
   (print! (start "Checking for Doom's prerequisites..."))
   (print-group!

core/core-lib.el

@@ -625,72 +625,7 @@ testing advice (when combined with `rotate-text').
 ;;
 ;;; Backports
 
-(eval-when! (version< emacs-version "27.0.90")
-  ;; DEPRECATED Backported from Emacs 27
-  (defmacro setq-local (&rest pairs)
-    "Make variables in PAIRS buffer-local and assign them the corresponding values.
-
-PAIRS is a list of variable/value pairs.  For each variable, make
-it buffer-local and assign it the corresponding value.  The
-variables are literal symbols and should not be quoted.
-
-The second VALUE is not computed until after the first VARIABLE
-is set, and so on; each VALUE can use the new value of variables
-set earlier in the ‘setq-local’.  The return value of the
-‘setq-local’ form is the value of the last VALUE.
-
-\(fn [VARIABLE VALUE]...)"
-    (declare (debug setq))
-    (unless (zerop (mod (length pairs) 2))
-      (error "PAIRS must have an even number of variable/value members"))
-    (let ((expr nil))
-      (while pairs
-        (unless (symbolp (car pairs))
-          (error "Attempting to set a non-symbol: %s" (car pairs)))
-        ;; Can't use backquote here, it's too early in the bootstrap.
-        (setq expr
-              (cons
-               (list 'set
-                     (list 'make-local-variable (list 'quote (car pairs)))
-                     (car (cdr pairs)))
-               expr))
-        (setq pairs (cdr (cdr pairs))))
-      (macroexp-progn (nreverse expr)))))
-
-(eval-when! (version< emacs-version "27.1")
-  ;; DEPRECATED Backported from Emacs 27. Remove when 26.x support is dropped.
-  (defun executable-find (command &optional remote)
-    "Search for COMMAND in `exec-path' and return the absolute file name.
-Return nil if COMMAND is not found anywhere in `exec-path'.  If
-REMOTE is non-nil, search on the remote host indicated by
-`default-directory' instead."
-    (if (and remote (file-remote-p default-directory))
-        (let ((res (locate-file
-                    command
-                    (mapcar
-                     (lambda (x) (concat (file-remote-p default-directory) x))
-                     (exec-path))
-                    exec-suffixes 'file-executable-p)))
-          (when (stringp res) (file-local-name res)))
-      ;; Use 1 rather than file-executable-p to better match the
-      ;; behavior of call-process.
-      (let ((default-directory
-              (let (file-name-handler-alist)
-                (file-name-quote default-directory))))
-        (locate-file command exec-path exec-suffixes 1)))))
-
-(eval-when! (not (fboundp 'exec-path))
-  ;; DEPRECATED Backported from Emacs 27.1. Remove when 26.x support is dropped.
-  (defun exec-path ()
-    "Return list of directories to search programs to run in remote subprocesses.
-The remote host is identified by `default-directory'.  For remote
-hosts that do not support subprocesses, this returns `nil'.
-If `default-directory' is a local directory, this function returns
-the value of the variable `exec-path'."
-    (let ((handler (find-file-name-handler default-directory 'exec-path)))
-      (if handler
-          (funcall handler 'exec-path)
-        exec-path))))
+;; None at the moment!
 
 (provide 'core-lib)
 ;;; core-lib.el ends here

core/core-ui.el

@@ -667,16 +667,17 @@ windows, switch to `doom-fallback-buffer'. Otherwise, delegate to original
   (dolist (fn '(switch-to-buffer display-buffer))
     (advice-add fn :around #'doom-run-switch-buffer-hooks-a)))
 
+;; Apply `doom-font' et co
+(add-hook 'doom-after-init-modules-hook #'doom-init-fonts-h -100)
+
 ;; Apply `doom-theme'
 (add-hook (if (daemonp)
               'after-make-frame-functions
             'doom-after-init-modules-hook)
-          #'doom-init-theme-h)
+          #'doom-init-theme-h
+          -90)
 
-;; Apply `doom-font' et co
-(add-hook 'doom-after-init-modules-hook #'doom-init-fonts-h)
-
-(add-hook 'window-setup-hook #'doom-init-ui-h 'append)
+(add-hook 'window-setup-hook #'doom-init-ui-h 100)
 
 
 ;;
@@ -702,25 +703,11 @@ windows, switch to `doom-fallback-buffer'. Otherwise, delegate to original
   (fset 'define-fringe-bitmap #'ignore))
 
 (after! whitespace
-  (defun doom-disable-whitespace-mode-in-childframes-a (orig-fn)
+  (defun doom-is-childframes-p ()
     "`whitespace-mode' inundates child frames with whitespace markers, so
 disable it to fix all that visual noise."
-    (unless (frame-parameter nil 'parent-frame)
-      (funcall orig-fn)))
-  (add-function :around whitespace-enable-predicate #'doom-disable-whitespace-mode-in-childframes-a))
-
-;; Don't display messages in the minibuffer when using the minibuffer
-;; DEPRECATED Remove when Emacs 26.x support is dropped.
-(eval-when! (not EMACS27+)
-  (defmacro doom-silence-motion-key (command key)
-    (let ((key-command (intern (format "doom/silent-%s" command))))
-      `(progn
-         (defun ,key-command ()
-           (interactive)
-           (ignore-errors (call-interactively ',command)))
-         (define-key minibuffer-local-map (kbd ,key) #',key-command))))
-  (doom-silence-motion-key backward-delete-char "<backspace>")
-  (doom-silence-motion-key delete-char "<delete>"))
+    (frame-parameter nil 'parent-frame))
+  (add-function :before-while whitespace-enable-predicate #'doom-is-childframes-p))
 
 (provide 'core-ui)
 ;;; core-ui.el ends here

core/core.el

@@ -355,7 +355,6 @@ config.el instead."
       (when (boundp 'libgnutls-version)
         (concat "SECURE128:+SECURE192:-VERS-ALL"
                 (if (and (not IS-WINDOWS)
-                         (not (version< emacs-version "26.3"))
                          (>= libgnutls-version 30605))
                     ":+VERS-TLS1.3")
                 ":+VERS-TLS1.2"))

core/packages.el

@@ -37,8 +37,6 @@
 (package! helpful :pin "7e4b1f0d5572a4e2b8ee7a9b084ef863d0315a73")
 (package! pcre2el :pin "0b5b2a2c173aab3fd14aac6cf5e90ad3bf58fa7d")
 (package! smartparens :pin "911cc896a0f2eb8b5fbdd6fc8331523ad9889a3a")
-;; DEPRECATED Built into Emacs 27+; remove when we drop 26 support
-(package! so-long :built-in 'prefer :pin "1da43ed63b5f9a8188eb8107bbad842d10831537")
 (package! ws-butler
   ;; Use my fork of ws-butler, which has a few choice improvements and
   ;; optimizations (the original has been abandoned).