Remove never-used rev argument from VC's backend checkin methods.

Alters vc/vc-arch.el, vc/vc-bzr.el, vc/vc-cvs.el, vc/vc-dav.el,
vc/vc-git.el, vc/vc-hg.el, vc/vc-mtn.el, vc/vc-rcs.el,
vc/vc-sccs.el, vc/vc-svn.el, vc/vc.el.

Only the RCS, SCCS, and CVS back ends tried to do anything with it,
and that code was never exercised. Chiseling away the cruft of
decades...

12 files changed, 74 insertions, 57 deletions

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index 6fa23de0244..2020fd34f37 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,12 @@
+2014-11-20  Eric S. Raymond  <esr@snark>
+
+        * vc/vc-arch.el, vc/vc-bzr.el, vc/vc-cvs.el, vc/vc-dav.el,
+        vc/vc-git.el, vc/vc-hg.el, vc/vc-mtn.el, vc/vc-rcs.el,
+        vc/vc-sccs.el, vc/vc-svn.el, vc/vc.el: Remove never-used rev
+        argument from the backend checkin methods. Only the RCS, SCCS, and
+        CVS back ends tried to do anything with it, and that code was
+        never exercised. Chiseling away the cruft of decades...
+
 2014-11-19  Lars Magne Ingebrigtsen  <larsi@gnus.org>
 
         * net/eww.el (eww-render): Remove a no-op :title setting.
diff --git a/lisp/vc/vc-arch.el b/lisp/vc/vc-arch.el
index 2bc8b7b4339..53b8e35ff93 100644
--- a/lisp/vc/vc-arch.el
+++ b/lisp/vc/vc-arch.el
@@ -441,8 +441,7 @@ CALLBACK expects (ENTRIES &optional MORE-TO-COME); see
 
 (autoload 'vc-switches "vc")
 
-(defun vc-arch-checkin (files rev comment)
-  (if rev (error "Committing to a specific revision is unsupported"))
+(defun vc-arch-checkin (files comment)
   ;; FIXME: This implementation probably only works for singleton filesets
   (let ((summary (file-relative-name (car files) (vc-arch-root (car files)))))
     ;; Extract a summary from the comment.
diff --git a/lisp/vc/vc-bzr.el b/lisp/vc/vc-bzr.el
index a093bcb6b92..2c1941bf6a8 100644
--- a/lisp/vc/vc-bzr.el
+++ b/lisp/vc/vc-bzr.el
@@ -634,10 +634,8 @@ or a superior directory.")
                                            "" (replace-regexp-in-string
                                                "\n[ \t]?" " " str)))))
 
-(defun vc-bzr-checkin (files rev comment)
-  "Check FILES in to bzr with log message COMMENT.
-REV non-nil gets an error."
-  (if rev (error "Can't check in a specific revision with bzr"))
+(defun vc-bzr-checkin (files comment)
+  "Check FILES in to bzr with log message COMMENT."
   (apply 'vc-bzr-command "commit" nil 0 files
          (cons "-m" (log-edit-extract-headers
                      `(("Author" . ,(vc-bzr--sanitize-header "--author"))
diff --git a/lisp/vc/vc-cvs.el b/lisp/vc/vc-cvs.el
index ad5559bb699..6fbfa727138 100644
--- a/lisp/vc/vc-cvs.el
+++ b/lisp/vc/vc-cvs.el
@@ -321,20 +321,38 @@ its parents."
                   (directory-file-name dir))))
     (eq dir t)))
 
-(defun vc-cvs-checkin (files rev comment)
+;; 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)
   "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" (if rev (concat "-r" rev))
-                       (concat "-m" comment)
+                       "ci" (concat "-m" comment)
                        (vc-switches 'CVS 'checkin))))
     (set-buffer "*vc*")
     (goto-char (point-min))
@@ -365,12 +383,7 @@ 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)
-
-    ;; 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-find-revision (file rev buffer)
   (apply 'vc-cvs-command
diff --git a/lisp/vc/vc-dav.el b/lisp/vc/vc-dav.el
index 9b67d74c779..77979d696d3 100644
--- a/lisp/vc/vc-dav.el
+++ b/lisp/vc/vc-dav.el
@@ -82,10 +82,8 @@ See `vc-checkout-model' for a list of possible values."
   ;; Do we need to do anything here?  FIXME?
   )
 
-(defun vc-dav-checkin (url rev comment)
-  "Commit changes in URL to WebDAV.
-If REV is non-nil, that should become the new revision number.
-COMMENT is used as a check-in comment."
+(defun vc-dav-checkin (url comment)
+  "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 3b11a3cd635..3e45eabee0e 100644
--- a/lisp/vc/vc-git.el
+++ b/lisp/vc/vc-git.el
@@ -665,7 +665,7 @@ 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 _rev comment)
+(defun vc-git-checkin (files comment)
   (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 4f13914aa2d..583fa6c6909 100644
--- a/lisp/vc/vc-hg.el
+++ b/lisp/vc/vc-hg.el
@@ -407,7 +407,7 @@ Optional arg REVISION is a revision to annotate from."
     (and (vc-hg-command nil 0 nil "status")
          (vc-hg-command nil 0 nil (if branchp "bookmark" "tag") name))))
 
-(defun vc-hg-retrieve-tag (dir name update)
+(defun vc-hg-retrieve-tag (dir name _update)
   "Retrieve the version tagged by NAME of all registered files at or below DIR."
   (let ((default-directory dir))
     (vc-hg-command nil 0 nil "update" name)
@@ -477,7 +477,7 @@ COMMENT is ignored."
 
 (declare-function log-edit-extract-headers "log-edit" (headers string))
 
-(defun vc-hg-checkin (files _rev comment)
+(defun vc-hg-checkin (files comment)
   "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 ea071c8586a..fdaca546afd 100644
--- a/lisp/vc/vc-mtn.el
+++ b/lisp/vc/vc-mtn.el
@@ -187,7 +187,7 @@ If nil, use the value of `vc-diff-switches'.  If t, use no switches."
 
 (declare-function log-edit-extract-headers "log-edit" (headers string))
 
-(defun vc-mtn-checkin (files _rev comment)
+(defun vc-mtn-checkin (files comment)
   (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 57515d04dc7..4b06b0923ba 100644
--- a/lisp/vc/vc-rcs.el
+++ b/lisp/vc/vc-rcs.el
@@ -358,23 +358,27 @@ whether to remove it."
          (yes-or-no-p (format "Directory %s is empty; remove it? " dir))
          (delete-directory dir))))
 
-(defun vc-rcs-checkin (files rev comment)
+;; 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)
   "RCS-specific version of `vc-backend-checkin'."
-  (let ((switches (vc-switches 'RCS 'checkin)))
+  (let (rev (switches (vc-switches 'RCS 'checkin)))
     ;; Now operate on the files
     (dolist (file (vc-expand-dirs files))
       (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 (not rev)
-             default-branch
+        (and default-branch
              (string-match (concat "^" (regexp-quote old-version) "\\.")
                            default-branch)
              (setq rev default-branch)
              (setq switches (cons "-f" switches)))
-        (if (and (not rev) old-version)
-            (setq rev (vc-branch-part old-version)))
+        (if old-version
+            (setq rev (vc-branch-part old-version))
+          (error "can't find current branch"))
         (apply #'vc-do-command "*vc*" 0 "ci" (vc-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 fb7d9596822..db777ab11e4 100644
--- a/lisp/vc/vc-sccs.el
+++ b/lisp/vc/vc-sccs.el
@@ -253,11 +253,10 @@ expanded if `vc-keep-workfiles' is non-nil, otherwise, delete the workfile."
       (stringp (vc-sccs-search-project-dir (or (file-name-directory file) "")
                                            (file-name-nondirectory file)))))
 
-(defun vc-sccs-checkin (files rev comment)
+(defun vc-sccs-checkin (files comment)
   "SCCS-specific version of `vc-backend-checkin'."
   (dolist (file (vc-expand-dirs files))
     (apply 'vc-sccs-do-command nil 0 "delta" (vc-name file)
-           (if rev (concat "-r" rev))
            (concat "-y" comment)
            (vc-switches 'SCCS 'checkin))
     (if vc-keep-workfiles
diff --git a/lisp/vc/vc-svn.el b/lisp/vc/vc-svn.el
index c7568e456f5..bd22fbf6a16 100644
--- a/lisp/vc/vc-svn.el
+++ b/lisp/vc/vc-svn.el
@@ -316,9 +316,8 @@ to the SVN command."
   "Return non-nil if FILE could be registered in SVN.
 This is only possible if SVN is responsible for FILE's directory.")
 
-(defun vc-svn-checkin (files rev comment &optional _extra-args-ignored)
+(defun vc-svn-checkin (files comment &optional _extra-args-ignored)
   "SVN-specific version of `vc-backend-checkin'."
-  (if rev (error "Committing to a specific revision is unsupported in SVN"))
   (let ((status (apply
                  'vc-svn-command nil 1 files "ci"
                  (nconc (list "-m" comment) (vc-switches 'SVN 'checkin)))))
diff --git a/lisp/vc/vc.el b/lisp/vc/vc.el
index 083849101d2..2efa4503a3a 100644
--- a/lisp/vc/vc.el
+++ b/lisp/vc/vc.el
@@ -72,7 +72,7 @@
 ;; When using Subversion or a later system, anything you do outside VC
 ;; *through the VCS tools* should safely interlock with VC
 ;; operations. Under these VC does little state caching, because local
-;; operations are assumed to be fast.  The dividing line is
+;; operations are assumed to be fast.
 ;;
 ;; ADDING SUPPORT FOR OTHER BACKENDS
 ;;
@@ -267,12 +267,12 @@
 ;;   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 rev comment)
+;; * checkin (files comment)
 ;;
-;;   Commit changes in FILES to this backend.  REV is a historical artifact
-;;   and should be ignored.  COMMENT is used as a check-in comment.
-;;   The implementation should pass the value of vc-checkin-switches to
-;;   the backend command.
+;;   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.
 ;;
 ;; * find-revision (file rev buffer)
 ;;
@@ -1498,13 +1498,11 @@ 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 rev comment initial-contents)
-  "Check in FILES.
-The optional argument REV may be a string specifying the new revision
-level (strongly deprecated).  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.
+(defun vc-checkin (files backend &optional comment initial-contents)
+  "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.
 
 If `vc-keep-workfiles' is nil, FILE is deleted afterwards, provided
 that the version control system supports this mode of operation.
@@ -1530,7 +1528,7 @@ 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 rev comment)
+         (vc-call-backend backend 'checkin files comment)
          (mapc 'vc-delete-automatic-version-backups files))
        `((vc-state . up-to-date)
          (vc-checkout-time . ,(nth 5 (file-attributes file)))
@@ -2686,7 +2684,7 @@ backend to NEW-BACKEND, and unregister FILE from the current backend.
     (when (or move edited)
       (vc-file-setprop file 'vc-state 'edited)
       (vc-mode-line file new-backend)
-      (vc-checkin file new-backend nil comment (stringp comment)))))
+      (vc-checkin file new-backend comment (stringp comment)))))
 
 (defun vc-rename-master (oldmaster newfile templates)
   "Rename OLDMASTER to be the master file for NEWFILE based on TEMPLATES."