Subject: bug#39564: 28.0.50; read-key function do not display the prompt if called from read-from-minibuffer

From: Oleh Krehel <[email-masked]>
Date: Tue, 11 Feb 2020 17:17:02 +0100

Hello,

Here's an updated code that works as intended on 26.3 and unexpected on 28.

(defun make-lines (n)
  (mapconcat #'number-to-string
             (number-sequence 0 n) "\n"))

(let ((map (make-sparse-keymap)))
  (define-key map (kbd "C-f") (lambda ()
                                (interactive)
                                (let ((inhibit-field-text-motion t))
                                  (goto-char (point-min)))
                                (message "%S"
                                         (read-key
                                          (concat
                                           (make-lines 10)
                                           "\nTest2")))
                                (minibuffer-keyboard-quit)))
  (read-from-minibuffer (concat (make-lines 10) "\nTest1: ") nil map))

The idea here is that the read-key hint will occupy as much space as
the initial read-from-minibuffer.

regards,
Oleh