Let ESC ESC quit in read-char-choice, and use it in userlock.el.

* lisp/subr.el (read-char-choice): Allow quitting via ESC ESC.

* lisp/userlock.el (ask-user-about-supersession-threat): Use
read-char-choice.

Fixes: debbugs:12093

1 files changed, 19 insertions, 29 deletions

diff --git a/lisp/userlock.el b/lisp/userlock.el
index 705d9588249..4c003e423aa 100644
--- a/lisp/userlock.el
+++ b/lisp/userlock.el
@@ -108,37 +108,27 @@ You can rewrite this to use any criterion you like to choose which one to do.
 The buffer in question is current when this function is called."
   (discard-input)
   (save-window-excursion
-    (let (answer)
+    (let ((prompt
+	   (format "%s changed on disk; \
+really edit the buffer? (y, n, r or C-h) "
+		   (file-name-nondirectory fn)))
+	  (choices '(?y ?n ?r ?? ?\C-h))
+	  answer)
       (while (null answer)
-	(message "%s changed on disk; really edit the buffer? (y, n, r or C-h) "
-		 (file-name-nondirectory fn))
-	(let ((tem (downcase (let ((cursor-in-echo-area t))
-			       (read-char-exclusive)))))
-	  (setq answer
-		(if (= tem help-char)
-		    'help
-		  (cdr (assoc tem '((?n . yield)
-				    (?\C-g . yield)
-				    (?y . proceed)
-				    (?r . revert)
-				    (?? . help))))))
-	  (cond ((null answer)
-		 (beep)
-		 (message "Please type y, n or r; or ? for help")
-		 (sit-for 3))
-		((eq answer 'help)
-		 (ask-user-about-supersession-help)
-		 (setq answer nil))
-		((eq answer 'revert)
-		 (revert-buffer nil (not (buffer-modified-p)))
-					; ask confirmation if buffer modified
-		 (signal 'file-supersession
-			 (list "File reverted" fn)))
-		((eq answer 'yield)
-		 (signal 'file-supersession
-			 (list "File changed on disk" fn))))))
+	(setq answer (read-char-choice prompt choices))
+	(cond ((memq answer '(?? ?\C-h))
+	       (ask-user-about-supersession-help)
+	       (setq answer nil))
+	      ((eq answer ?r)
+	       ;; Ask for confirmation if buffer modified
+	       (revert-buffer nil (not (buffer-modified-p)))
+	       (signal 'file-supersession
+		       (list "File reverted" fn)))
+	      ((eq answer ?n)
+	       (signal 'file-supersession
+		       (list "File changed on disk" fn)))))
       (message
-        "File on disk now will become a backup file if you save these changes.")
+       "File on disk now will become a backup file if you save these changes.")
       (setq buffer-backed-up nil))))
 
 (defun ask-user-about-supersession-help ()