Make describe-face also output the version information

* lisp/help-fns.el (describe-variable-custom-version-info): Allow
taking a type as an optional input, so this can be used for faces,
too (bug#30527).

* lisp/faces.el (describe-face): Use this to output the version
information.

2 files changed, 16 insertions, 6 deletions

diff --git a/lisp/faces.el b/lisp/faces.el
index f9e8c6c58b8..c3ef7dcb0f7 100644
--- a/lisp/faces.el
+++ b/lisp/faces.el
@@ -25,6 +25,8 @@
 
 ;;; Code:
 
+(require 'subr-x)
+
 (defcustom term-file-prefix (purecopy "term/")
   "If non-nil, Emacs startup performs terminal-specific initialization.
 It does this by: (load (concat term-file-prefix (getenv \"TERM\")))
@@ -1416,6 +1418,8 @@ argument, prompt for a regular expression using `read-regexp'."
         (dolist (face (face-list))
           (copy-face face face frame disp-frame)))))
 
+(declare-function describe-variable-custom-version-info "help-fns"
+                  (variable &optional type))
 
 (defun describe-face (face &optional frame)
   "Display the properties of face FACE on FRAME.
@@ -1428,6 +1432,7 @@ If FRAME is omitted or nil, use the selected frame."
   (interactive (list (read-face-name "Describe face"
                                      (or (face-at-point t) 'default)
                                      t)))
+  (require 'help-fns)
   (let* ((attrs '((:family . "Family")
                   (:foundry . "Foundry")
                   (:width . "Width")
@@ -1524,7 +1529,11 @@ If FRAME is omitted or nil, use the selected frame."
                           (re-search-backward ": \\([^:]+\\)" nil t)
                           (help-xref-button 1 'help-face attr)))
                     (insert "\n")))))
-            (terpri)))))))
+            (terpri)
+            (when-let ((version-info (describe-variable-custom-version-info
+                                      f 'face)))
+              (insert version-info))
+            (terpri)))))))
 
 
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
diff --git a/lisp/help-fns.el b/lisp/help-fns.el
index 39f701ae2a8..0b5c547d6b0 100644
--- a/lisp/help-fns.el
+++ b/lisp/help-fns.el
@@ -860,14 +860,15 @@ If ANY-SYMBOL is non-nil, don't insist the symbol be bound."
                 (and (or any-symbol (boundp sym)) sym)))))
         0)))
 
-(defun describe-variable-custom-version-info (variable)
+(defun describe-variable-custom-version-info (variable &optional type)
   (let ((custom-version (get variable 'custom-version))
         (cpv (get variable 'custom-package-version))
+        (type (or type "variable"))
         (output nil))
     (if custom-version
         (setq output
-              (format "This variable was introduced, or its default value was changed, in\nversion %s of Emacs.\n"
-                      custom-version))
+              (format "This %s was introduced, or its default value was changed, in\nversion %s of Emacs.\n"
+                      type custom-version))
       (when cpv
         (let* ((package (car-safe cpv))
                (version (if (listp (cdr-safe cpv))
@@ -877,11 +878,11 @@ If ANY-SYMBOL is non-nil, don't insist the symbol be bound."
                (emacsv (cdr (assoc version pkg-versions))))
           (if (and package version)
               (setq output
-                    (format (concat "This variable was introduced, or its default value was changed, in\nversion %s of the %s package"
+                    (format (concat "This %s was introduced, or its default value was changed, in\nversion %s of the %s package"
                                     (if emacsv
                                         (format " that is part of Emacs %s" emacsv))
                                     ".\n")
-                            version package))))))
+                            type version package))))))
     output))
 
 ;;;###autoload