message uses minibuffer-message in the active minibuffer (bug#17272 bug#19064)

* doc/lispref/display.texi (Displaying Messages): Explain the
behavior of using minibuffer-message if the minibuffer is active.

* src/editfns.c (Fmessage_in_echo_area): New function with body
copied from Fmessage.
(Fmessage): Call minibuffer-message in the active minibuffer,
otherwise call Fmessage_in_echo_area.
(message-in-echo-area): New variable.

* lisp/isearch.el (isearch--momentary-message, isearch-message):
* lisp/minibuffer.el (minibuffer-message, minibuffer-completion-help):
Use 'message-in-echo-area' instead of 'message' where necessary.

* lisp/autorevert.el (auto-revert-handler):
* lisp/man.el (Man-bgproc-sentinel):
* lisp/subr.el (do-after-load-evaluation):
Revert recent changes that replaced 'message' with 'minibuffer-message'.
This is not needed anymore since 'message' uses 'minibuffer-message'
in the active minibuffer.

doc/lispref/display.texi

@@ -276,11 +276,13 @@ followed by a newline.
 When @code{inhibit-message} is non-@code{nil}, no message will be displayed
 in the echo area, it will only be logged to @samp{*Messages*}.
 
+If the minibuffer is active, it uses the @code{minibuffer-message}
+function to display the message temporarily at the end of the
+minibuffer (@pxref{Minibuffer Misc}).
+
 If @var{format-string} is @code{nil} or the empty string,
 @code{message} clears the echo area; if the echo area has been
-expanded automatically, this brings it back to its normal size.  If
-the minibuffer is active, this brings the minibuffer contents back
-onto the screen immediately.
+expanded automatically, this brings it back to its normal size.
 
 @example
 @group

etc/NEWS

@@ -754,6 +754,10 @@ the minibuffer.  If non-nil, point will move to the end of the prompt
 *** Minibuffer now uses 'minibuffer-message' to display error messages
 at the end of the active minibuffer.
 
++++
+*** The function 'message' now displays the message at the end of the minibuffer
+when the minibuffer is active.
+
 +++
 *** 'y-or-n-p' now uses the minibuffer to read 'y' or 'n' answer.
 

lisp/autorevert.el

@@ -815,8 +815,7 @@ This is an internal function used by Auto-Revert Mode."
     (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.

lisp/isearch.el

@@ -2011,7 +2011,7 @@ Turning on character-folding turns off regexp mode.")
 (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 +3168,7 @@ If there is no completion possible, say so and continue searching."
 	     (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.

lisp/man.el

@@ -1474,7 +1474,7 @@ manpage command."
           (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.

lisp/minibuffer.el

@@ -712,16 +712,16 @@ If ARGS are provided, then pass MESSAGE through `format-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.
@@ -1840,7 +1840,7 @@ variables.")
 (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))
@@ -1851,7 +1851,7 @@ variables.")
                        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)))

lisp/subr.el

@@ -4607,7 +4607,7 @@ This function is called directly from the C code."
 			               (string-match "\\.elc?\\>" file))
                             obarray))
 	   (msg (format "Package %s is deprecated" package))
-	   (fun (lambda (msg) (minibuffer-message "%s" msg))))
+	   (fun (lambda (msg) (message "%s" msg))))
       ;; Cribbed from cl--compiling-file.
       (when (or (not (fboundp 'byte-compile-warning-enabled-p))
                 (byte-compile-warning-enabled-p 'obsolete package))

src/editfns.c

@@ -2875,8 +2875,58 @@ 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'.
 
+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 (Factive_minibuffer_window ())
+      && 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 +4570,11 @@ This variable is experimental; email 32252@debbugs.gnu.org if you need
 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 +4649,7 @@ it to be non-nil.  */);
   defsubr (&Semacs_pid);
   defsubr (&Ssystem_name);
   defsubr (&Smessage);
+  defsubr (&Smessage_in_echo_area);
   defsubr (&Smessage_box);
   defsubr (&Smessage_or_box);
   defsubr (&Scurrent_message);