From f74dd1cd87987ea7faf0cfc6240c2284ef9133cb Mon Sep 17 00:00:00 2001
From: brotzeit <brotzeitmacher@gmail.com>
Date: Tue, 27 Dec 2022 19:16:44 +0100
Subject: provide alternative rust-mode that derives from rust-ts-mode

---
 rust-mode.el | 70 +++++++++---------------------------------------------------
 1 file changed, 10 insertions(+), 60 deletions(-)

(limited to 'rust-mode.el')

diff --git a/rust-mode.el b/rust-mode.el
index 4bb1bcb..0c68c43 100644
--- a/rust-mode.el
+++ b/rust-mode.el
@@ -88,6 +88,13 @@ to the function arguments.  When nil, `->' will be indented one level."
   :group 'rust-mode
   :safe #'booleanp)
 
+(defcustom rust-mode-treesitter-derive nil
+  "Whether rust-mode should derive from the new treesitter mode `rust-ts-mode'
+instead of `prog-mode'. This option requires emacs29+."
+  :version "29.1"
+  :type 'boolean
+  :group 'rustic)
+
 ;;; Faces
 
 (define-obsolete-face-alias 'rust-unsafe-face
@@ -250,66 +257,9 @@ See `prettify-symbols-compose-predicate'."
     map)
   "Keymap for Rust major mode.")
 
-;;;###autoload
-(define-derived-mode rust-mode prog-mode "Rust"
-  "Major mode for Rust code.
-
-\\{rust-mode-map}"
-  :group 'rust-mode
-  :syntax-table rust-mode-syntax-table
-
-  ;; Syntax
-  (setq-local syntax-propertize-function #'rust-syntax-propertize)
-
-  ;; Indentation
-  (setq-local indent-line-function 'rust-mode-indent-line)
-
-  ;; Fonts
-  (setq-local font-lock-defaults
-              '(rust-font-lock-keywords
-                nil nil nil nil
-                (font-lock-syntactic-face-function
-                 . rust-mode-syntactic-face-function)))
-
-  ;; Misc
-  (setq-local comment-start "// ")
-  (setq-local comment-end   "")
-  (setq-local open-paren-in-column-0-is-defun-start nil)
-
-  ;; Auto indent on }
-  (setq-local electric-indent-chars
-              (cons ?} (and (boundp 'electric-indent-chars)
-                            electric-indent-chars)))
-
-  ;; Allow paragraph fills for comments
-  (setq-local comment-start-skip "\\(?://[/!]*\\|/\\*[*!]?\\)[[:space:]]*")
-  (setq-local paragraph-start
-              (concat "[[:space:]]*\\(?:"
-                      comment-start-skip
-                      "\\|\\*/?[[:space:]]*\\|\\)$"))
-  (setq-local paragraph-separate paragraph-start)
-  (setq-local normal-auto-fill-function #'rust-do-auto-fill)
-  (setq-local fill-paragraph-function #'rust-fill-paragraph)
-  (setq-local fill-forward-paragraph-function #'rust-fill-forward-paragraph)
-  (setq-local adaptive-fill-function #'rust-find-fill-prefix)
-  (setq-local adaptive-fill-first-line-regexp "")
-  (setq-local comment-multi-line t)
-  (setq-local comment-line-break-function #'rust-comment-indent-new-line)
-  (setq-local imenu-generic-expression rust-imenu-generic-expression)
-  (setq-local imenu-syntax-alist '((?! . "w"))) ; For macro_rules!
-  (setq-local beginning-of-defun-function #'rust-beginning-of-defun)
-  (setq-local end-of-defun-function #'rust-end-of-defun)
-  (setq-local parse-sexp-lookup-properties t)
-  (setq-local electric-pair-inhibit-predicate
-              #'rust-electric-pair-inhibit-predicate-wrap)
-  (add-function :before-until (local 'electric-pair-skip-self)
-                #'rust-electric-pair-skip-self)
-  ;; Configure prettify
-  (setq prettify-symbols-alist rust-prettify-symbols-alist)
-  (setq prettify-symbols-compose-predicate #'rust--prettify-symbols-compose-p)
-
-  (add-hook 'before-save-hook rust-before-save-hook nil t)
-  (add-hook 'after-save-hook rust-after-save-hook nil t))
+(if (and (version<= "29.1" emacs-version) rust-mode-treesitter-derive)
+    (require 'rust-mode-treesitter)
+  (require 'rust-prog-mode))
 
 ;;;###autoload
 (add-to-list 'auto-mode-alist '("\\.rs\\'" . rust-mode))
-- 
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