Add completion-header-string.

* doc/emacs/mini.texi (completion-header-string): Remove
completion-header-text-property-list and completion-lazy-count.
(completion-header-string): Substitutes the removed variable.

doc/emacs/mini.texi

@@ -667,17 +667,14 @@ control of the Completion window display properties you can use
 Alists,,Action Alists for Buffer Display, elisp, The Emacs Lisp
 Reference Manual}).
 
-@vindex completion-lazy-count
-@vindex completion-header-text-property-list
-  When the boolean variable @code{completion-lazy-count} is
-non-@code{nil} the completions header line shows the total number of
-completion candidates.  With the text property list
-@code{completion-header-text-property-list} (@pxref{Property
-Lists,,Property Lists, elisp, The Emacs Lisp Reference Manual}) the
-user can specify some text properties to the completions header line.
-Some useful values may be @code{face}, @code{cursor-intangible} or
-@code{invisible} (@pxref{Special Properties,,Properties with Special
-Meanings, elisp, The Emacs Lisp Reference Manual}).
+@vindex completion-header-string
+The variable @code{completion-header-string} is a string to control
+the message shown before completions.  It may contain a ``%s'' to show
+the total number of completions.  If nil no completions are shown.
+Text properties may be added to change the appearance, some useful
+ones are @code{face} or @code{cursor-intangible} (@pxref{Special
+Properties,,Properties with Special Meanings, elisp, The Emacs Lisp
+Reference Manual}).
 
 @vindex completions-highlight-mode
 When the mode @code{completions-highlight-mode} is active the candidate

etc/NEWS

@@ -568,13 +568,10 @@ some completion is made.
 This option limits the height of the "*Completions*" buffer.
 
 +++
-*** New option 'completion-header-text-property-list'
-List of text properties to add to the header line of completions.
-
-+++
-*** New option 'completion-lazy-count'
-When non-nil the completions header line shows the total number of
-completion candidates.
+*** New option 'completion-header-string'
+This is a string to control the message to show before completions.
+It may contain a %s to show the total number of completions. If nil no
+completions are shown.
 
 +++
 *** New mode 'completions-highlight-mode'.

lisp/minibuffer.el

@@ -1873,18 +1873,12 @@ completions."
   :type 'boolean
   :version "28.1")
 
-(defcustom completion-header-text-property-list nil
-  "List of text properties to add to the header line of completions.
-For example you can change the header color to red setting this
-to: `(face (:foreground ``red'')).  Some useful properties may be
-`cursor-intangible' or `invisible'.  See Info node `(elisp) Special
-Properties'."
-  :type 'plist
-  :version "29.1")
-
-(defcustom completion-lazy-count nil
-  "When non-nil, display the total number of candidates in the completions header."
-  :type 'boolean
+(defcustom completion-header-string "Possible completions are (%s):\n"
+  "Propertized header text for completions list.
+It may contain one %s to show the total count of completions.
+When nil no header is shown."
+  :type '(choice (const :tag "No prefix" nil)
+                 (string :tag "Prefix format string"))
   :version "29.1")
 
 (defun completion--insert-strings (strings &optional group-fun)
@@ -2149,18 +2143,11 @@ candidates."
 
     (with-current-buffer standard-output
       (goto-char (point-max))
-      (if completions
-          (let ((start (point))
-                (text (concat
-                       "Possible completions are"
-                       (if completion-lazy-count
-                           (format " (%s)" (length completions)))
-                       ":\n")))
-            (insert text)
-            (when completion-header-text-property-list
-              (add-text-properties start (point) completion-header-text-property-list))
-            (completion--insert-strings completions group-fun))
-        (insert "There are no possible completions of what you have typed."))))
+      (if (not completions)
+          (insert "There are no possible completions of what you have typed.")
+        (when completion-header-string
+          (insert (format completion-header-string (length completions))))
+        (completion--insert-strings completions group-fun))))
 
   (run-hooks 'completion-setup-hook)
   nil)