Resurrect the ability to specify a revision in vc-next-action

* lisp/vc/vc-bzr.el (vc-bzr-checkin):
* lisp/vc/vc-dav.el (vc-dav-checkin):
* lisp/vc/vc-git.el (vc-git-checkin):
* lisp/vc/vc-hg.el (vc-hg-checkin):
* lisp/vc/vc-mtn.el (vc-mtn-checkin): Accept and silently ignore
an additional optional argument, the revision to checkin.

* lisp/vc/vc-sccs.el (vc-sccs-checkin):
* lisp/vc/vc-cvs.el (vc-cvs-checkin):
* lisp/vc/vc-rcs.el (vc-rcs-checkin): Allow to optionally specify
a revision to checkin.

* lisp/vc/vc.el (vc-next-action): Allow to optionally specify the
revision when checking in files.

See http://lists.gnu.org/archive/html/emacs-devel/2015-09/msg00688.html
for the details.

9 files changed, 47 insertions, 56 deletions

diff --git a/lisp/vc/vc-bzr.el b/lisp/vc/vc-bzr.el
index 5f8dd0bf0e8..9b2711d8146 100644
--- a/lisp/vc/vc-bzr.el
+++ b/lisp/vc/vc-bzr.el
@@ -649,7 +649,7 @@ or a superior directory.")
                                            "" (replace-regexp-in-string
                                                "\n[ \t]?" " " str)))))
 
-(defun vc-bzr-checkin (files comment)
+(defun vc-bzr-checkin (files comment &optional _rev)
   "Check FILES in to bzr with log message COMMENT."
   (apply 'vc-bzr-command "commit" nil 0 files
          (cons "-m" (log-edit-extract-headers
diff --git a/lisp/vc/vc-cvs.el b/lisp/vc/vc-cvs.el
index 73ef42ac7d6..5f5807fb3c6 100644
--- a/lisp/vc/vc-cvs.el
+++ b/lisp/vc/vc-cvs.el
@@ -332,38 +332,20 @@ its parents."
                   (directory-file-name dir))))
     (eq dir t)))
 
-;; vc-cvs-checkin used to take a 'rev' second argument that allowed
-;; checking in onto a specified branch tip rather than the current
-;; default branch, but nothing in the entire rest of VC exercised
-;; this code.  Removing it simplifies the backend interface for all
-;; modes.
-;;
-;; Here's the setup code preserved in amber, in case the logic needs
-;; to be broken out into a method someday; (if rev (concat "-r" rev))
-;; used to be part of the switches passed to vc-cvs-command.
-;;
-;;  (unless (or (not rev) (vc-cvs-valid-revision-number-p rev))
-;;    (if (not (vc-cvs-valid-symbolic-tag-name-p rev))
-;;      (error "%s is not a valid symbolic tag name" rev)
-;;      ;; If the input revision is a valid symbolic tag name, we create it
-;;      ;; as a branch, commit and switch to it.
-;;      (apply 'vc-cvs-command nil 0 files "tag" "-b" (list rev))
-;;      (apply 'vc-cvs-command nil 0 files "update" "-r" (list rev))
-;;      (mapc (lambda (file) (vc-file-setprop file 'vc-cvs-sticky-tag rev))
-;;          files)))
-;;
-;; The following postamble cleaned up after the branch change:
-;;
-;;    ;; if this was an explicit check-in (does not include creation of
-;;    ;; a branch), remove the sticky tag.
-;;    (if (and rev (not (vc-cvs-valid-symbolic-tag-name-p rev)))
-;;      (vc-cvs-command nil 0 files "update" "-A"))))
-;;        files)))
-;;
-(defun vc-cvs-checkin (files comment)
+(defun vc-cvs-checkin (files comment &optional rev)
   "CVS-specific version of `vc-backend-checkin'."
+ (unless (or (not rev) (vc-cvs-valid-revision-number-p rev))
+   (if (not (vc-cvs-valid-symbolic-tag-name-p rev))
+        (error "%s is not a valid symbolic tag name" rev)
+     ;; If the input revision is a valid symbolic tag name, we create it
+     ;; as a branch, commit and switch to it.
+     (apply 'vc-cvs-command nil 0 files "tag" "-b" (list rev))
+     (apply 'vc-cvs-command nil 0 files "update" "-r" (list rev))
+     (mapc (lambda (file) (vc-file-setprop file 'vc-cvs-sticky-tag rev))
+            files)))
   (let ((status (apply 'vc-cvs-command nil 1 files
-                       "ci" (concat "-m" comment)
+                       "ci" (if rev (concat "-r" rev))
+                       (concat "-m" comment)
                        (vc-switches 'CVS 'checkin))))
     (set-buffer "*vc*")
     (goto-char (point-min))
@@ -394,7 +376,11 @@ its parents."
     ;; tell it from the permissions of the file (see
     ;; vc-cvs-checkout-model).
     (mapc (lambda (file) (vc-file-setprop file 'vc-checkout-model nil))
-          files)))
+          files)
+    ;; if this was an explicit check-in (does not include creation of
+    ;; a branch), remove the sticky tag.
+    (if (and rev (not (vc-cvs-valid-symbolic-tag-name-p rev)))
+        (vc-cvs-command nil 0 files "update" "-A"))))
 
 (defun vc-cvs-find-revision (file rev buffer)
   (apply 'vc-cvs-command
diff --git a/lisp/vc/vc-dav.el b/lisp/vc/vc-dav.el
index 3326f2964c9..880e14be63e 100644
--- a/lisp/vc/vc-dav.el
+++ b/lisp/vc/vc-dav.el
@@ -82,7 +82,7 @@ See `vc-checkout-model' for a list of possible values."
   ;; Do we need to do anything here?  FIXME?
   )
 
-(defun vc-dav-checkin (url comment)
+(defun vc-dav-checkin (url comment &optional _rev)
   "Commit changes in URL to WebDAV. COMMENT is used as a check-in comment."
   ;; This should PUT the resource and release any locks that we hold.
   )
diff --git a/lisp/vc/vc-git.el b/lisp/vc/vc-git.el
index 8a0f5547c4d..2f0439365e8 100644
--- a/lisp/vc/vc-git.el
+++ b/lisp/vc/vc-git.el
@@ -674,7 +674,7 @@ If toggling on, also insert its message into the buffer."
   "Major mode for editing Git log messages.
 It is based on `log-edit-mode', and has Git-specific extensions.")
 
-(defun vc-git-checkin (files comment)
+(defun vc-git-checkin (files comment &optional _rev)
   (let* ((file1 (or (car files) default-directory))
          (root (vc-git-root file1))
          (default-directory (expand-file-name root))
diff --git a/lisp/vc/vc-hg.el b/lisp/vc/vc-hg.el
index f634e2eac53..49573986125 100644
--- a/lisp/vc/vc-hg.el
+++ b/lisp/vc/vc-hg.el
@@ -465,7 +465,7 @@ Optional arg REVISION is a revision to annotate from."
 
 (declare-function log-edit-extract-headers "log-edit" (headers string))
 
-(defun vc-hg-checkin (files comment)
+(defun vc-hg-checkin (files comment &optional _rev)
   "Hg-specific version of `vc-backend-checkin'.
 REV is ignored."
   (apply 'vc-hg-command nil 0 files
diff --git a/lisp/vc/vc-mtn.el b/lisp/vc/vc-mtn.el
index 685ef3b6742..b56a08f2a9e 100644
--- a/lisp/vc/vc-mtn.el
+++ b/lisp/vc/vc-mtn.el
@@ -199,7 +199,7 @@ switches."
 
 (declare-function log-edit-extract-headers "log-edit" (headers string))
 
-(defun vc-mtn-checkin (files comment)
+(defun vc-mtn-checkin (files comment &optional _rev)
   (apply 'vc-mtn-command nil 0 files
          (nconc (list "commit" "-m")
                 (log-edit-extract-headers '(("Author" . "--author")
diff --git a/lisp/vc/vc-rcs.el b/lisp/vc/vc-rcs.el
index 995bd059f2d..ba1336424ea 100644
--- a/lisp/vc/vc-rcs.el
+++ b/lisp/vc/vc-rcs.el
@@ -306,27 +306,23 @@ whether to remove it."
            (yes-or-no-p (format "Directory %s is empty; remove it? " dir))
            (delete-directory dir)))))
 
-;; It used to be possible to pass in a value for the variable rev, but
-;; nothing in the rest of VC used this capability.  Removing it makes the
-;; backend interface simpler for all modes.
-;;
-(defun vc-rcs-checkin (files comment)
+(defun vc-rcs-checkin (files comment &optional rev)
   "RCS-specific version of `vc-backend-checkin'."
-  (let (rev (switches (vc-switches 'RCS 'checkin)))
+  (let ((switches (vc-switches 'RCS 'checkin)))
     ;; Now operate on the files
     (dolist (file (vc-expand-dirs files 'RCS))
       (let ((old-version (vc-working-revision file)) new-version
             (default-branch (vc-file-getprop file 'vc-rcs-default-branch)))
         ;; Force branch creation if an appropriate
         ;; default branch has been set.
-        (and default-branch
+        (and (not rev)
+             default-branch
              (string-match (concat "^" (regexp-quote old-version) "\\.")
                            default-branch)
              (setq rev default-branch)
              (setq switches (cons "-f" switches)))
-        (if old-version
-            (setq rev (vc-branch-part old-version))
-          (error "can't find current branch"))
+        (if (and (not rev) old-version)
+            (setq rev (vc-branch-part old-version)))
         (apply #'vc-do-command "*vc*" 0 "ci" (vc-master-name file)
                ;; if available, use the secure check-in option
                (and (vc-rcs-release-p "5.6.4") "-j")
diff --git a/lisp/vc/vc-sccs.el b/lisp/vc/vc-sccs.el
index 8d8d9e844ed..a3facc56d5d 100644
--- a/lisp/vc/vc-sccs.el
+++ b/lisp/vc/vc-sccs.el
@@ -222,10 +222,11 @@ to the SCCS command."
       (stringp (vc-sccs-search-project-dir (or (file-name-directory file) "")
                                            (file-name-nondirectory file)))))
 
-(defun vc-sccs-checkin (files comment)
+(defun vc-sccs-checkin (files comment &optional rev)
   "SCCS-specific version of `vc-backend-checkin'."
   (dolist (file (vc-expand-dirs files 'SCCS))
     (apply 'vc-sccs-do-command nil 0 "delta" (vc-master-name file)
+           (if rev (concat "-r" rev))
            (concat "-y" comment)
            (vc-switches 'SCCS 'checkin))
         (vc-sccs-do-command nil 0 "get" (vc-master-name file))))
diff --git a/lisp/vc/vc.el b/lisp/vc/vc.el
index 90d450a5ab9..f08e562efe5 100644
--- a/lisp/vc/vc.el
+++ b/lisp/vc/vc.el
@@ -233,12 +233,13 @@
 ;;   Unregister FILE from this backend.  This is only needed if this
 ;;   backend may be used as a "more local" backend for temporary editing.
 ;;
-;; * checkin (files comment)
+;; * checkin (files comment &optional rev)
 ;;
 ;;   Commit changes in FILES to this backend. COMMENT is used as a
 ;;   check-in comment.  The implementation should pass the value of
-;;   vc-checkin-switches to the backend command.  The revision argument
-;;   of some older VC versions is no longer supported.
+;;   vc-checkin-switches to the backend command.  The optional REV
+;;   revision argument is only supported with some older VCSes, like
+;;   RCS and CVS, and is otherwise silently ignored.
 ;;
 ;; * find-revision (file rev buffer)
 ;;
@@ -1221,10 +1222,15 @@ For old-style locking-based version control systems, like RCS:
             (message "No files remain to be committed")
           (if (not verbose)
               (vc-checkin ready-for-commit backend)
-            (let ((new-backend (vc-read-backend "New backend: ")))
-              (if new-backend
-                  (dolist (file files)
-                    (vc-transfer-file file new-backend))))))))
+            (let* ((revision (read-string "New revision or backend: "))
+                   (revision-downcase (downcase revision)))
+              (if (member
+                   revision-downcase
+                   (mapcar (lambda (arg) (downcase (symbol-name arg)))
+                           vc-handled-backends))
+                  (let ((vsym (intern revision-downcase)))
+                    (dolist (file files) (vc-transfer-file file vsym)))
+                (vc-checkin ready-for-commit backend nil nil revision)))))))
      ;; locked by somebody else (locking VCSes only)
      ((stringp state)
       ;; In the old days, we computed the revision once and used it on
@@ -1522,11 +1528,13 @@ Type \\[vc-next-action] to check in changes.")
      ".\n")
     (message "Please explain why you stole the lock.  Type C-c C-c when done.")))
 
-(defun vc-checkin (files backend &optional comment initial-contents)
+(defun vc-checkin (files backend &optional comment initial-contents rev)
   "Check in FILES. COMMENT is a comment string; if omitted, a
 buffer is popped up to accept a comment.  If INITIAL-CONTENTS is
 non-nil, then COMMENT is used as the initial contents of the log
 entry buffer.
+The optional argument REV may be a string specifying the new revision
+level (only supported for some older VCSes, like RCS and CVS).
 
 Runs the normal hooks `vc-before-checkin-hook' and `vc-checkin-hook'."
   (when vc-before-checkin-hook
@@ -1549,7 +1557,7 @@ Runs the normal hooks `vc-before-checkin-hook' and `vc-checkin-hook'."
        ;; vc-checkin-switches, but 'the' local buffer is
        ;; not a well-defined concept for filesets.
        (progn
-         (vc-call-backend backend 'checkin files comment)
+         (vc-call-backend backend 'checkin files comment rev)
          (mapc 'vc-delete-automatic-version-backups files))
        `((vc-state . up-to-date)
          (vc-checkout-time . ,(nth 5 (file-attributes file)))