fix(lib): doom/set-indent-width on Emacs >=30

A built-in `editorconfig` package was added in Emacs 30, with a somewhat
different API from the other package of the same name.

Fix: #8072

lisp/lib/text.el

@@ -368,7 +368,15 @@ editorconfig or dtrt-indent installed."
   (setq-local standard-indent width)
   (when (boundp 'evil-shift-width)
     (setq evil-shift-width width))
-  (cond ((require 'editorconfig nil t)
+  ;; REVIEW: Only use `editorconfig' once we drop 29.x support.
+  (cond ((let ((load-path (get 'load-path 'initial-value)))
+           ;; A built-in `editorconfig' package was added in Emacs 30.x, but
+           ;; with a different API. Since it's built in, prefer it over the
+           ;; upstream one, but we still need to adapt:
+           (require 'editorconfig nil t))
+         (pcase-dolist (`(,var . ,val) (editorconfig--default-indent-size-function width))
+           (set (make-local-variable var) val)))
+        ((require 'editorconfig nil t)
          (let (editorconfig-lisp-use-default-indent)
            (editorconfig-set-indentation nil width)))
         ((require 'dtrt-indent nil t)
@@ -376,7 +384,7 @@ editorconfig or dtrt-indent installed."
            (dolist (var (ensure-list vars))
              (doom-log "Updated %s = %d" var width)
              (set var width)))))
-  (message "Changed indentation to %d" width))
+  (message "Changed buffer's indent-size to %d" width))
 
 
 ;;

modules/tools/editorconfig/config.el

@@ -1,5 +1,6 @@
 ;;; tools/editorconfig/config.el -*- lexical-binding: t; -*-
 
+;; TODO: Adapt to built-in `editorconfig' in Emacs 30+
 ;; Handles whitespace (tabs/spaces) settings externally. This way projects can
 ;; specify their own formatting rules.
 (use-package! editorconfig