From 226e689b1183a34f3b611185201416e4f3205304 Mon Sep 17 00:00:00 2001
From: Sean Whitton <spwhitton@spwhitton.name>
Date: Fri, 16 Dec 2022 22:34:52 -0700
Subject: [PATCH] vc-prepare-patch: Number the attached patches

* lisp/gnus/mml.el (mml-attach-buffer): New FILENAME argument.
* lisp/vc/vc.el (vc-prepare-patch): When vc-prepare-patches-separately
is nil, generate file names for the attached patches.  The file names
begin with numbers indicating the ordering of the patches.
---
 lisp/gnus/mml.el | 13 ++++++++-----
 lisp/vc/vc.el    | 26 +++++++++++++++++++++-----
 2 files changed, 29 insertions(+), 10 deletions(-)

diff --git a/lisp/gnus/mml.el b/lisp/gnus/mml.el
index ebd0adf2e25..dc86fe6db96 100644
--- a/lisp/gnus/mml.el
+++ b/lisp/gnus/mml.el
@@ -1484,10 +1484,12 @@ mml-dnd-attach-file
 	  (setq disposition (mml-minibuffer-read-disposition type nil file)))
 	(mml-attach-file file type description disposition)))))
 
-(defun mml-attach-buffer (buffer &optional type description disposition)
+(defun mml-attach-buffer (buffer &optional type description disposition filename)
   "Attach a buffer to the outgoing MIME message.
 BUFFER is the name of the buffer to attach.  See
-`mml-attach-file' for details of operation."
+`mml-attach-file' regarding TYPE, DESCRIPTION and DISPOSITION.
+FILENAME is a suggested file name for the attachment should a
+recipient wish to save a copy separate from the message."
   (interactive
    (let* ((buffer (read-buffer "Attach buffer: "))
 	  (type (mml-minibuffer-read-type buffer "text/plain"))
@@ -1497,9 +1499,10 @@ mml-attach-buffer
   ;; If in the message header, attach at the end and leave point unchanged.
   (let ((head (unless (message-in-body-p) (point))))
     (if head (goto-char (point-max)))
-    (mml-insert-empty-tag 'part 'type type 'buffer buffer
-			  'disposition disposition
-			  'description description)
+    (apply #'mml-insert-empty-tag
+           'part 'type type 'buffer buffer
+	   'disposition disposition 'description description
+           (and filename `(filename ,filename)))
     ;; When using Mail mode, make sure it does the mime encoding
     ;; when you send the message.
     (or (eq mail-user-agent 'message-user-agent)
diff --git a/lisp/vc/vc.el b/lisp/vc/vc.el
index 690c907c77e..ed10909fee8 100644
--- a/lisp/vc/vc.el
+++ b/lisp/vc/vc.el
@@ -3466,11 +3466,27 @@ vc-prepare-patch
         (rfc822-goto-eoh)
         (forward-line)
         (save-excursion
-          (dolist (patch patches)
-            (mml-attach-buffer (buffer-name (plist-get patch :buffer))
-                               "text/x-patch"
-                               (plist-get patch :subject)
-                               "attachment")))
+          (let ((i 0))
+            (dolist (patch patches)
+              (let* ((patch-subject (plist-get patch :subject))
+                     (stripped-subject
+                      (replace-regexp-in-string
+                       "^\\[.*PATCH.*\\]\\s-*" "" patch-subject))
+                     (filename
+                      (concat
+                       (string-trim
+                        (replace-regexp-in-string
+                         "\\W" "-" (if (length> stripped-subject 50)
+                                       (substring stripped-subject 0 50)
+                                     stripped-subject))
+                        "-+" "-+")
+                       ".patch")))
+                (mml-attach-buffer
+                 (buffer-name (plist-get patch :buffer))
+                 "text/x-patch"
+                 patch-subject
+                 "attachment"
+                 (format "%04d-%s" (cl-incf i) filename))))))
         (open-line 2)))))
 
 (defun vc-default-responsible-p (_backend _file)
-- 
2.30.2