Re-add rustic mode based on rustic-ts (Treesitter support)

This code is based on #480, but
there are some changes based on my testing.

README.md

@@ -143,6 +143,16 @@ rustfmt and most of the common cargo commands should work remotely.
 We are currently updating the code base. If you encounter any command
 that doesn't work remotely, please open an issue.
 
+## TreeSitter
+
+You can try the new native treesitter mode `rust-ts-mode` with:
+
+```elisp
+(use-package rustic
+  :init
+  (setq rustic-treesitter-derive t))
+```
+
 ## Compilation
 
 ![](https://raw.githubusercontent.com/brotzeit/rustic/master/img/compilation_buffer.png)

rustic-rust-mode.el

@@ -0,0 +1,34 @@
+;;; rustic-rust-mode.el --- rust-mode related code -*-lexical-binding: t-*-
+;;; Commentary:
+
+;; Deprecated code related to rust-mode
+
+;;; Code:
+
+(setq rust-load-optional-libraries nil)
+(setq rust-before-save-hook #'rustic-before-save-hook)
+(setq rust-after-save-hook #'rustic-after-save-hook)
+(require 'rust-mode)
+
+;;; Define aliases for removed rustic functions
+
+(defvaralias 'rustic-indent-offset 'rust-indent-offset)
+(defvaralias 'rustic-indent-method-chain 'rust-indent-method-chain)
+(defvaralias 'rustic-indent-where-clause 'rust-indent-where-clause)
+(defvaralias 'rustic-match-angle-brackets 'rust-match-angle-brackets)
+(defvaralias 'rustic-indent-return-type-to-arguments 'rust-indent-return-type-to-arguments)
+(defalias 'rustic-indent-line #'rust-mode-indent-line)
+(defalias 'rustic-end-of-defun #'rust-end-of-defun)
+
+;;;###autoload
+(define-derived-mode rustic-mode rust-mode "Rustic"
+  "Major mode for Rust code.
+
+\\{rustic-mode-map}"
+  :group 'rustic
+
+  (when (bound-and-true-p rustic-cargo-auto-add-missing-dependencies)
+   (add-hook 'lsp-after-diagnostics-hook 'rustic-cargo-add-missing-dependencies-hook nil t)))
+
+(provide 'rustic-rust-mode)
+;;; rustic-rust-mode.el ends here

rustic-ts-mode.el

@@ -0,0 +1,25 @@
+;;; rustic-ts-mode.el --- use native rust-ts-mode -*-lexical-binding: t-*-
+;;; Commentary:
+
+;; Derive from rust-ts-mode instead of rust-mode
+
+;;; Code:
+
+;;; For the save hooks this is required
+(require 'rustic-rustfmt)
+
+
+;;;###autoload
+(define-derived-mode rustic-mode rust-ts-mode "Rustic (TS)"
+  "Major mode for Rust code.
+
+\\{rustic-mode-map}"
+  :group 'rustic
+
+  (when (bound-and-true-p rustic-cargo-auto-add-missing-dependencies)
+    (add-hook 'lsp-after-diagnostics-hook 'rustic-cargo-add-missing-dependencies-hook nil t))
+  (add-hook 'before-save-hook 'rustic-before-save-hook nil t)
+  (add-hook 'after-save-hook 'rustic-after-save-hook nil t))
+
+(provide 'rustic-ts-mode)
+;;; rustic-ts-mode.el ends here

rustic.el

@@ -34,11 +34,8 @@
 (require 'subr-x)
 
 (require 'dash)
-
-(setq rust-load-optional-libraries nil)
-(setq rust-before-save-hook #'rustic-before-save-hook)
-(setq rust-after-save-hook #'rustic-after-save-hook)
-(require 'rust-mode)
+(when (version<= "29.1" emacs-version)
+  (require 'treesit))
 
 ;;; Customization
 
@@ -47,16 +44,6 @@
   :link '(url-link "https://www.rustic-lang.org/")
   :group 'languages)
 
-;;; Define aliases for removed rustic functions
-
-(defvaralias 'rustic-indent-offset 'rust-indent-offset)
-(defvaralias 'rustic-indent-method-chain 'rust-indent-method-chain)
-(defvaralias 'rustic-indent-where-clause 'rust-indent-where-clause)
-(defvaralias 'rustic-match-angle-brackets 'rust-match-angle-brackets)
-(defvaralias 'rustic-indent-return-type-to-arguments 'rust-indent-return-type-to-arguments)
-(defalias 'rustic-indent-line #'rust-mode-indent-line)
-(defalias 'rustic-end-of-defun #'rust-end-of-defun)
-
 ;;; workaround for with-temp-buffer not propagating the environment, as per
 ;;; https://github.com/magit/magit/pull/4169
 (defmacro rustic--with-temp-process-buffer (&rest body)
@@ -75,6 +62,14 @@ as for that macro."
          (setq-local exec-path ,e)
          ,@body))))
 
+(defcustom rustic-treesitter-derive nil
+  "Whether rustic should derive from the new treesitter mode
+`rust-ts-mode'. If not, it derives from `rust-mode'. This option
+requires emacs29+"
+  :version "29.1"
+  :type 'boolean
+  :group 'rustic)
+
 ;;; Workspace
 
 (defvar-local rustic--buffer-workspace nil
@@ -152,24 +147,18 @@ this variable."
     map)
   "Keymap for `rustic-mode'.")
 
-;;;###autoload
-(define-derived-mode rustic-mode rust-mode "Rustic"
-  "Major mode for Rust code.
-
-\\{rustic-mode-map}"
-  :group 'rustic
+(defun activate-rustic-mode ()
+  (if (and (version<= "29.1" emacs-version) rustic-treesitter-derive)
+    (if (treesit-ready-p 'rust t)
+        (require 'rustic-ts-mode)
+      (require 'rustic-rust-mode))
+    (require 'rustic-rust-mode)))
 
-  (when (bound-and-true-p rustic-cargo-auto-add-missing-dependencies)
-   (add-hook 'lsp-after-diagnostics-hook 'rustic-cargo-add-missing-dependencies-hook nil t)))
+(activate-rustic-mode)
 
 ;;;###autoload
 (add-to-list 'auto-mode-alist '("\\.rs\\'" . rustic-mode))
 
-;; remove rust-mode from `auto-mode-alist'
-(let ((mode '("\\.rs\\'" . rust-mode)))
-  (when (member mode auto-mode-alist)
-    (setq auto-mode-alist (remove mode auto-mode-alist))))
-
 ;;; envrc support
 
 ;; To support envrc, it is necessary to wrap any buffer creation code