Subject: bug#17272: bug#19064: bug#17272: bug#19064: 25.0.50; `message' overwrites `y-or-n-p' prompt, so user misses it

From: Juri Linkov <[email-masked]>
Date: Sat, 23 Nov 2019 23:54:01 +0200

>>> The variable name is ‘message-in-echo-area’.  After a little testing,
>>> it seems to handle all such cases well:
>>
>> I have not tested the patch, but it looks good to me.
>
> Actually this patch needs more testing.  I found already
> two cases that might be annoying.  Better to anticipate
> a possible angry reaction and fix these cases in advance.

After more testing, at least all noticed problems are fixed
with this patch (it also reverts previous commits that
added minibuffer-message and that is not needed anymore):

diff --git a/lisp/autorevert.el b/lisp/autorevert.el
index 079750a3f6..9275513c8d 100644
--- a/lisp/autorevert.el
+++ b/lisp/autorevert.el
@@ -815,8 +815,7 @@ auto-revert-handler
     (when revert
       (when (and auto-revert-verbose
                  (not (eq revert 'fast)))
-        (with-current-buffer (window-buffer (old-selected-window))
-          (minibuffer-message "Reverting buffer `%s'." (buffer-name))))
+        (message "Reverting buffer `%s'." (buffer-name)))
       ;; If point (or a window point) is at the end of the buffer, we
       ;; want to keep it at the end after reverting.  This allows one
       ;; to tail a file.
diff --git a/lisp/isearch.el b/lisp/isearch.el
index 4f3342782d..1705b050b5 100644
--- a/lisp/isearch.el
+++ b/lisp/isearch.el
@@ -2011,7 +2011,7 @@ isearch-message-properties
 (defun isearch--momentary-message (string)
   "Print STRING at the end of the isearch prompt for 1 second."
   (let ((message-log-max nil))
-    (message "%s%s%s"
+    (message-in-echo-area "%s%s%s"
              (isearch-message-prefix nil isearch-nonincremental)
              isearch-message
              (apply #'propertize (format " [%s]" string)
@@ -3168,7 +3170,7 @@ isearch-message
 	     (isearch-message-prefix ellipsis isearch-nonincremental)
 	     m
 	     (isearch-message-suffix c-q-hack)))
-    (if c-q-hack m (let ((message-log-max nil)) (message "%s" m)))))
+    (if c-q-hack m (let ((message-log-max nil)) (message-in-echo-area "%s" m)))))
 
 (defun isearch--describe-regexp-mode (regexp-function &optional space-before)
   "Make a string for describing REGEXP-FUNCTION.
diff --git a/lisp/man.el b/lisp/man.el
index ce01fdc805..beec2e616f 100644
--- a/lisp/man.el
+++ b/lisp/man.el
@@ -1474,7 +1474,7 @@ Man-bgproc-sentinel
           (kill-buffer Man-buffer)))
 
       (when message
-        (minibuffer-message "%s" message)))))
+        (message "%s" message)))))
 
 (defun Man-page-from-arguments (args)
   ;; Skip arguments and only print the page name.
diff --git a/lisp/minibuffer.el b/lisp/minibuffer.el
index ee3d0095a9..7c87a18273 100644
--- a/lisp/minibuffer.el
+++ b/lisp/minibuffer.el
@@ -712,16 +712,16 @@ minibuffer-message
       (progn
         (if args
             (apply #'message message args)
-          (message "%s" message))
+          (message-in-echo-area "%s" message))
         (prog1 (sit-for (or minibuffer-message-timeout 1000000))
-          (message nil)))
+          (message-in-echo-area nil)))
     ;; Record message in the *Messages* buffer
     (let ((inhibit-message t))
       (if args
           (apply #'message message args)
-        (message "%s" message)))
+        (message-in-echo-area "%s" message)))
     ;; Clear out any old echo-area message to make way for our new thing.
-    (message nil)
+    (message-in-echo-area nil)
     (setq message (if (and (null args)
                            (string-match-p "\\` *\\[.+\\]\\'" message))
                       ;; Make sure we can put-text-property.
@@ -1838,7 +1838,7 @@ completion--done
 (defun minibuffer-completion-help (&optional start end)
   "Display a list of possible completions of the current minibuffer contents."
   (interactive)
-  (message "Making completion list...")
+  (message-in-echo-area "Making completion list...")
   (let* ((start (or start (minibuffer-prompt-end)))
          (end (or end (point-max)))
          (string (buffer-substring start end))
@@ -1849,7 +1849,7 @@ minibuffer-completion-help
                        minibuffer-completion-predicate
                        (- (point) start)
                        md)))
-    (message nil)
+    (message-in-echo-area nil)
     (if (or (null completions)
             (and (not (consp (cdr completions)))
                  (equal (car completions) string)))
diff --git a/lisp/subr.el b/lisp/subr.el
index 20daed623f..fae06399ef 100644
--- a/lisp/subr.el
+++ b/lisp/subr.el
@@ -4620,9 +4620,10 @@ do-after-load-evaluation
 					  byte-compile-current-file
 					  byte-compile-root-dir)))
 	      (byte-compile-warn "%s" msg))
-	  (run-with-idle-timer 0 nil
+	  (run-with-timer 0 nil
 			  (lambda (msg)
-			    (minibuffer-message "%s" msg))
+			    (discard-input)
+			    (message "%s" msg))
 			  msg)))))
 
   ;; Finally, run any other hook.
diff --git a/src/editfns.c b/src/editfns.c
index 8fc866d391..650dc6d4ca 100644
--- a/src/editfns.c
+++ b/src/editfns.c
@@ -2875,8 +2875,57 @@ accent (\\=`) and apostrophe (\\=') are special in the format; see
 any existing message; this lets the minibuffer contents show.  See
 also `current-message'.
 
+When the variable `message-in-echo-area' is non-nil, use the function
+`message-in-echo-area' to display the message in the echo area.
+Otherwise, when the minibuffer is active, use `minibuffer-message'
+to temporarily display the message at the end of the minibuffer.
+
 usage: (message FORMAT-STRING &rest ARGS)  */)
   (ptrdiff_t nargs, Lisp_Object *args)
+{
+  if (NILP (Vmessage_in_echo_area)
+      && !inhibit_message
+      && !(NILP (args[0]) || (STRINGP (args[0]) && SBYTES (args[0]) == 0))
+      && WINDOW_LIVE_P (Fold_selected_window ())
+      && BUFFERP (Fwindow_buffer (Fold_selected_window ()))
+      && !NILP (Fminibufferp (Fwindow_buffer (Fold_selected_window ()))))
+    {
+      ptrdiff_t count = SPECPDL_INDEX ();
+
+      /* Avoid possible recursion.  */
+      specbind (Qmessage_in_echo_area, Qt);
+
+      record_unwind_current_buffer ();
+      Fset_buffer (Fwindow_buffer (Fold_selected_window ()));
+
+      return unbind_to (count, CALLN (Fapply, intern ("minibuffer-message"),
+                                      Flist (nargs, args)));
+    }
+  else
+    return Fmessage_in_echo_area (nargs, args);
+}
+
+DEFUN ("message-in-echo-area", Fmessage_in_echo_area, Smessage_in_echo_area, 1, MANY, 0,
+       doc: /* Display a message at the bottom of the screen.
+The message also goes into the `*Messages*' buffer, if `message-log-max'
+is non-nil.  (In keyboard macros, that's all it does.)
+Return the message.
+
+In batch mode, the message is printed to the standard error stream,
+followed by a newline.
+
+The first argument is a format control string, and the rest are data
+to be formatted under control of the string.  Percent sign (%), grave
+accent (\\=`) and apostrophe (\\=') are special in the format; see
+`format-message' for details.  To display STRING without special
+treatment, use (message-in-echo-area "%s" STRING).
+
+If the first argument is nil or the empty string, the function clears
+any existing message; this lets the minibuffer contents show.  See
+also `current-message'.
+
+usage: (message-in-echo-area FORMAT-STRING &rest ARGS)  */)
+  (ptrdiff_t nargs, Lisp_Object *args)
 {
   if (NILP (args[0])
       || (STRINGP (args[0])
@@ -4520,6 +4569,11 @@ syms_of_editfns (void)
 it to be non-nil.  */);
   binary_as_unsigned = false;
 
+  DEFVAR_LISP ("message-in-echo-area", Vmessage_in_echo_area,
+	       doc: /* Non-nil means overwrite the minibuffer with a message in the echo area.  */);
+  Vmessage_in_echo_area = Qnil;
+  DEFSYM (Qmessage_in_echo_area, "message-in-echo-area");
+
   defsubr (&Spropertize);
   defsubr (&Schar_equal);
   defsubr (&Sgoto_char);
@@ -4594,6 +4648,7 @@ syms_of_editfns (void)
   defsubr (&Semacs_pid);
   defsubr (&Ssystem_name);
   defsubr (&Smessage);
+  defsubr (&Smessage_in_echo_area);
   defsubr (&Smessage_box);
   defsubr (&Smessage_or_box);
   defsubr (&Scurrent_message);