bug#57400: 29.0.50; Support sending patches from VC directly

[Philip Kaludercic]

Here is an updated version of the patch:

>From a384a0b74e8037c642ac49dbad9489fd51f6c8cd Mon Sep 17 00:00:00 2001
From: Philip Kaludercic <philipk@posteo.net>
Date: Mon, 3 Oct 2022 20:54:38 +0200
Subject: [PATCH] Add a VC command to prepare patches

* doc/emacs/vc1-xtra.texi (Miscellaneous VC):  Add new node.
(Editing VC Commands):  Document new feature.
* etc/NEWS:  Mention 'vc-prepare-patch'.
* lisp/vc/log-view.el: Autoload 'log-view-get-marked'.
* lisp/vc/vc-git.el (vc-git-prepare-patch):  Add Git implementation.
* lisp/vc/vc-hg.el (vc-git-prepare-patch):  Add Mercurial implementation.
* lisp/vc/vc-bzr.el (vc-git-prepare-patch):  Add Bazaar implementation.
* lisp/vc/vc.el (vc-read-revision):  Add a MULTIPLE argument.
(vc-read-multiple-revisions):  Add an auxiliary function that always
calls 'vc-read-revision' with a non-nil value for MULTIPLE.
(vc-prepare-patches-inline):  Add user option.
(message-goto-body):  Declare function.
(message--name-table):  Declare function.
(vc-default-prepare-patch): Add a default implementation.
(vc-prepare-patch):  Add command.  (bug#57400)
---
 doc/emacs/vc1-xtra.texi |  26 +++++++++
 etc/NEWS                |  15 +++++
 lisp/vc/log-view.el     |   1 +
 lisp/vc/vc-bzr.el       |  14 +++++
 lisp/vc/vc-git.el       |  24 ++++++++
 lisp/vc/vc-hg.el        |  12 ++++
 lisp/vc/vc.el           | 121 ++++++++++++++++++++++++++++++++++++++--
 7 files changed, 209 insertions(+), 4 deletions(-)

diff --git a/doc/emacs/vc1-xtra.texi b/doc/emacs/vc1-xtra.texi
index 05d2144380..523e4611f0 100644
--- a/doc/emacs/vc1-xtra.texi
+++ b/doc/emacs/vc1-xtra.texi
@@ -16,6 +16,7 @@ Miscellaneous VC
 * Revision Tags::       Symbolic names for revisions.
 * Version Headers::     Inserting version control headers into working files.
 * Editing VC Commands:: Editing the VC shell commands that Emacs will run.
+* Preparing Patches::   Preparing and Composing patches from within VC
 @end menu
 
 @node Change Logs and VC
@@ -282,6 +283,31 @@ Editing VC Commands
 additional branches to the end of the @samp{git log} command that VC
 is about to run.
 
+@node Preparing Patches
+@subsubsection Preparing Patches
+
+@findex vc-prepare-patch
+When collaborating on projects it is common to send patches via Email,
+to share changes.  If you wish to do this using VC, you can use the
+@code{vc-prepare-patch} command.  This will prompt you which revisions
+you wish to share and who the addressee is.  The command will then use
+your @abbr{MUA, Mail User Agent} for you to review and send out.
+
+@vindex vc-prepare-patches-inline
+Depending on configuration of the user option
+@code{vc-prepare-patches-inline}, @code{vc-prepare-patch} will either
+generate a single or multiple messages.  A @code{nil} value (the default)
+will prepare and display a message for each revision, one after
+another.  A non-@code{nil} value will have all patches attached to the
+body of a single message.
+
+@vindex vc-default-patch-addressee
+If you expect to contribute patches on a regular basis, you can set
+the user option @code{vc-default-patch-addressee} to the address you
+wish to use.  This will be used as the default value when invoking
+@code{vc-prepare-patch}.  Project maintainers may consider setting
+this as a directory local variable (@pxref{Directory Variables}).
+
 @node Customizing VC
 @subsection Customizing VC
 
diff --git a/etc/NEWS b/etc/NEWS
index 0fa24c577c..78c607f0e9 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -1846,6 +1846,14 @@ Git commands display summary lines.  See the two new 
user options
 It is used to style the line that separates the 'log-edit' headers
 from the 'log-edit' summary.
 
++++
+*** New 'vc-prepare-patch' command.
+Patches for any version control system can be prepared using VC.  The
+command will query what commits to send and will compose messages for
+your mail user agent.  The behaviour of 'vc-prepare-patch' can be
+modified by the user options 'vc-prepare-patches-inline' and
+'vc-default-patch-addressee'.
+
 ** Message
 
 ---
@@ -2043,6 +2051,13 @@ The new ':doc-spec-function' element can be used to 
compute the
 ':doc-spec' element when the user asks for info on that particular
 mode (instead of at load time).
 
+** Subr-x
+
+---
+*** New macro 'with-funcall-substitutions'.
+The macro can be used to generically substitute function symbols in
+expressions.
+
 ** Ansi-color
 
 ---
diff --git a/lisp/vc/log-view.el b/lisp/vc/log-view.el
index 415b1564ed..7a710386fe 100644
--- a/lisp/vc/log-view.el
+++ b/lisp/vc/log-view.el
@@ -359,6 +359,7 @@ log-view-toggle-mark-entry
            (overlay-put ov 'log-view-self ov)
            (overlay-put ov 'log-view-marked (nth 1 entry))))))))
 
+;;;###autoload
 (defun log-view-get-marked ()
   "Return the list of tags for the marked log entries."
   (save-excursion
diff --git a/lisp/vc/vc-bzr.el b/lisp/vc/vc-bzr.el
index bce7996712..6f77f99555 100644
--- a/lisp/vc/vc-bzr.el
+++ b/lisp/vc/vc-bzr.el
@@ -1324,6 +1324,20 @@ vc-bzr-repository-url
           (match-string 1)
         (error "Cannot determine Bzr repository URL")))))
 
+(defun vc-bzr-prepare-patch (rev)
+  (with-current-buffer (generate-new-buffer " *vc-bzr-prepare-patch*")
+    (vc-bzr-command
+     "send" t 0 '()
+     "--revision" (concat (vc-bzr-previous-revision nil rev) ".." rev)
+     "--output" "-")
+    (let (subject)
+      ;; Extract the subject line
+      (goto-char (point-min))
+      (search-forward-regexp "^[^#].*")
+      (setq subject (match-string 0))
+      ;; Return the extracted data
+      (list :subject subject :buffer (current-buffer)))))
+
 (provide 'vc-bzr)
 
 ;;; vc-bzr.el ends here
diff --git a/lisp/vc/vc-git.el b/lisp/vc/vc-git.el
index 4a2a42ad2a..f9dae8b9ea 100644
--- a/lisp/vc/vc-git.el
+++ b/lisp/vc/vc-git.el
@@ -95,6 +95,7 @@
 ;; - find-file-hook ()                             OK
 ;; - conflicted-files                              OK
 ;; - repository-url (file-or-dir)                  OK
+;; - prepare-patch (rev)                           OK
 
 ;;; Code:
 
@@ -1742,6 +1743,29 @@ vc-git-extra-status-menu
 (defun vc-git-root (file)
   (vc-find-root file ".git"))
 
+(defun vc-git-prepare-patch (rev)
+  (with-current-buffer (generate-new-buffer " *vc-git-prepare-patch*")
+    (vc-git-command
+     t 0 '()  "format-patch"
+     "--no-numbered" "--stdout"
+     ;; From gitrevisions(7): ^<n> means the <n>th parent
+     ;; (i.e.  <rev>^ is equivalent to <rev>^1). As a
+     ;; special rule, <rev>^0 means the commit itself and
+     ;; is used when <rev> is the object name of a tag
+     ;; object that refers to a commit object.
+     (concat rev "^.." rev))
+    (let (subject)
+      ;; Extract the subject line
+      (goto-char (point-min))
+      (search-forward-regexp "^Subject: \\(.+\\)")
+      (setq subject (match-string 1))
+      ;; Jump to the beginning for the patch
+      (search-forward-regexp "\n\n")
+      ;; Return the extracted data
+      (list :subject subject
+            :buffer (current-buffer)
+            :body-start (point)))))
+
 ;; grep-compute-defaults autoloads grep.
 (declare-function grep-read-regexp "grep" ())
 (declare-function grep-read-files "grep" (regexp))
diff --git a/lisp/vc/vc-hg.el b/lisp/vc/vc-hg.el
index eed9592378..2eebe2d543 100644
--- a/lisp/vc/vc-hg.el
+++ b/lisp/vc/vc-hg.el
@@ -80,6 +80,7 @@
 ;; - delete-file (file)                        TEST IT
 ;; - rename-file (old new)                     OK
 ;; - find-file-hook ()                         added for bug#10709
+;; - prepare-patch (rev)                       OK
 
 ;; 2) Implement Stefan Monnier's advice:
 ;; vc-hg-registered and vc-hg-state
@@ -1507,6 +1508,17 @@ vc-hg-merge-branch
     (with-current-buffer buffer (vc-run-delayed (vc-compilation-mode 'hg)))
     (vc-set-async-update buffer)))
 
+(defun vc-hg-prepare-patch (rev)
+  (with-current-buffer (generate-new-buffer " *vc-hg-prepare-patch*")
+    (vc-hg-command t 0 '() "export" "--rev" rev)
+    (let (subject)
+      ;; Extract the subject line
+      (goto-char (point-min))
+      (search-forward-regexp "^[^#].*")
+      (setq subject (match-string 0))
+      ;; Return the extracted data
+      (list :subject subject :buffer (current-buffer)))))
+
 ;;; Internal functions
 
 (defun vc-hg-command (buffer okstatus file-or-list &rest flags)
diff --git a/lisp/vc/vc.el b/lisp/vc/vc.el
index f0f5ee504c..f0bd1023ac 100644
--- a/lisp/vc/vc.el
+++ b/lisp/vc/vc.el
@@ -574,6 +574,14 @@
 ;;   containing FILE-OR-DIR.  The optional REMOTE-NAME specifies the
 ;;   remote (in Git parlance) whose URL is to be returned.  It has
 ;;   only a meaning for distributed VCS and is ignored otherwise.
+;;
+;; - prepare-patch (rev)
+;;
+;;   Prepare a patch and return a property list with the keys
+;;   `:subject' indicating the patch message as a string, `:body'
+;;   containing the contents of the patch as a string (excluding the
+;;   header) and `:filename' pointing to a file where the patch has
+;;   been stored.
 
 ;;; Changes from the pre-25.1 API:
 ;;
@@ -1910,7 +1918,7 @@ vc-diff-internal
 (defvar vc-revision-history nil
   "History for `vc-read-revision'.")
 
-(defun vc-read-revision (prompt &optional files backend default initial-input)
+(defun vc-read-revision (prompt &optional files backend default initial-input 
multiple)
   (cond
    ((null files)
     (let ((vc-fileset (vc-deduce-fileset t))) ;FIXME: why t?  --Stef
@@ -1923,9 +1931,16 @@ vc-read-revision
          (completion-table
           (vc-call-backend backend 'revision-completion-table files)))
     (if completion-table
-        (completing-read prompt completion-table
-                         nil nil initial-input 'vc-revision-history default)
-      (read-string prompt initial-input nil default))))
+        (funcall
+         (if multiple #'completing-read-multiple #'completing-read)
+         prompt completion-table nil nil initial-input 'vc-revision-history 
default)
+      (let ((answer (read-string prompt initial-input nil default)))
+        (if multiple
+            (split-string answer "[ \t]*,[ \t]*")
+          answer)))))
+
+(defun vc-read-multiple-revisions (prompt &optional files backend default 
initial-input)
+  (vc-read-revision prompt files backend default initial-input t))
 
 (defun vc-diff-build-argument-list-internal (&optional fileset)
   "Build argument list for calling internal diff functions."
@@ -3237,6 +3252,104 @@ vc-update-change-log
   (vc-call-backend (vc-responsible-backend default-directory)
                    'update-changelog args))
 
+(defcustom vc-prepare-patches-inline nil
+  "Non-nil means that `vc-prepare-patch' creates a single message.
+A single message is created by attaching all patches to the body
+of a single message.  If nil, each patch will be sent out in a
+separate message, which will be prepared sequentially."
+  :type 'boolean
+  :safe #'booleanp
+  :version "29.1")
+
+(defcustom vc-default-patch-addressee nil
+  "Default addressee for `vc-prepare-patch'.
+If nil, no default will be used.  This option may be set locally."
+  :type '(choice (const :tag "No default" nil) string)
+  :safe #'stringp
+  :version "29.1")
+
+(declare-function message--name-table "message" (orig-string))
+(declare-function mml-attach-buffer "mml"
+                  (buffer &optional type description disposition))
+(declare-function log-view-get-marked "log-view" ())
+
+(defun vc-default-prepare-patch (rev)
+  (let ((backend (vc-backend buffer-file-name)))
+    (with-current-buffer (generate-new-buffer " *vc-default-prepare-patch*")
+      (vc-diff-internal
+       nil (list backend) rev
+       (vc-call-backend backend 'previous-revision
+                        buffer-file-name rev)
+       nil t)
+      (list :subject (concat "Patch for "
+                             (file-name-nondirectory
+                              (directory-file-name
+                               (vc-root-dir))))
+            :buffer (current-buffer)))))
+
+;;;###autoload
+(defun vc-prepare-patch (addressee subject revisions)
+  "Compose an Email sending patches for REVISIONS to ADDRESSEE.
+If `vc-prepare-patches-inline' is non-nil, SUBJECT will be used
+as the default subject for the message.  Otherwise a separate
+message will be composed for each revision.
+
+When invoked interactively in a Log View buffer with marked
+revisions, these revisions will be used."
+  (interactive
+   (let ((revs (or (log-view-get-marked)
+                   (vc-read-multiple-revisions "Revisions: ")))
+         to)
+     (require 'message)
+     (while (null (setq to (completing-read-multiple
+                            (format-prompt
+                             "Addressee"
+                             vc-default-patch-addressee)
+                            (message--name-table "")
+                            nil nil nil nil
+                            vc-default-patch-addressee)))
+       (message "At least one addressee required.")
+       (sit-for blink-matching-delay))
+     (list (string-join to ", ")
+           (and vc-prepare-patches-inline
+                (read-string "Subject: " "[PATCH] " nil nil t))
+           revs)))
+  (save-current-buffer
+    (vc-ensure-vc-buffer)
+    (let ((patches (mapcar (lambda (rev)
+                             (vc-call-backend
+                              (vc-responsible-backend default-directory)
+                              'prepare-patch rev))
+                           revisions)))
+      (if (not vc-prepare-patches-inline)
+          (dolist (patch patches)
+            (compose-mail addressee
+                          (plist-get patch :subject)
+                          nil nil nil nil
+                          `((kill-buffer ,(plist-get patch :buffer))
+                            (exit-recursive-edit)))
+            (rfc822-goto-eoh) (forward-line)
+            (save-excursion             ;don't jump to the end
+              (insert-buffer-substring
+               (plist-get patch :buffer)
+               (plist-get patch :body-start)
+               (plist-get patch :body-end)))
+            (recursive-edit))
+        (compose-mail addressee subject nil nil nil nil
+                      (mapcar
+                       (lambda (p)
+                         (list #'kill-buffer (plist-get p :buffer)))
+                       patches))
+        (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")))
+        (open-line 2)))))
+
 (defun vc-default-responsible-p (_backend _file)
   "Indicate whether BACKEND is responsible for FILE.
 The default is to return nil always."
-- 
2.37.3

It includes

- some documentation for the Emacs manual and etc/NEWS,

- a revised "prepare-patch" interface that uses buffers instead of
  temporary files (I hope this improves the encoding issue),

- use log-view commits if anything is marked,

- removed hard-coded `message-goto-body' calls,

- added bzr and hg support,

- A new user option 'vc-default-patch-addressee'.

Antoine Kalmbach <ane@iki.fi> writes:

>> +(defun vc-compose-patch (addressee subject revisions)
>> +  "Compose a message sending REVISIONS to ADDRESSEE with SUBJECT."
>> +  (interactive (save-current-buffer
>
> Overall, this looks great.  If I understand this right, this doesn't
> support entering revision ranges (abcd1234..ghjk568, HEAD~2, etc), but
> you have to input each absolute revision?  I think that's actually fine,
> because it composes with the proposed vc-log feature of marking commits
> there and then applying vc-compose-patch on the commits.  Trying to
> convert those into VCS specific revision ranges is probably asking for 
> trouble.

Yes, though the previous version of that patch didn't do this, and
instead just passed the commit directly to "git format-patch", which
isn't what the documentation claims the command does.