rust--after-revert-hook should preserve point position.

Otherwise, rust-format-buffer always moves point to the end of the
buffer.

Author: Wilfred

rust-mode-tests.el

@@ -2561,6 +2561,18 @@ Fontification needs to include this whole string or none of it.
     )
   )
 
+(ert-deftest rust-test-revert-hook-preserves-point ()
+  (with-temp-buffer
+    ;; Insert some code, and put point in the middle.
+    (insert "fn foo() {}\n")
+    (insert "fn bar() {}\n")
+    (insert "fn baz() {}\n")
+    (goto-char (point-min))
+    (forward-line 1)
+    (let ((initial-point (point)))
+      (rust--after-revert-hook)
+      (should (equal initial-point (point))))))
+
 ;; If electric-pair-mode is available, load it and run the tests that use it.  If not,
 ;; no error--the tests will be skipped.
 (require 'elec-pair nil t)

rust-mode.el

@@ -1365,9 +1365,10 @@ This is written mainly to be used as `end-of-defun-function' for Rust."
   ;; to use `font-lock-ensure', which doesn't exist in Emacs 24 and earlier.
   ;; If it's not available, fall back to calling `font-lock-fontify-region'
   ;; on the whole buffer.
-  (if (fboundp 'font-lock-ensure)
-      (font-lock-ensure)
-    (font-lock-fontify-region (point-min) (point-max))))
+  (save-excursion
+    (if (fboundp 'font-lock-ensure)
+        (font-lock-ensure)
+      (font-lock-fontify-region (point-min) (point-max)))))
 
 (defun rust--before-save-hook ()
   (when rust-format-on-save (rust-format-buffer)))