(with-vc-file, vc-next-action-on-file):

Use vc-backend rather than vc-registered.
(vc-next-action-on-file): Use intern-soft.
Deal with read-only *vc-diff* buffer.
(vc-switch-backend): Short circuit if nothing is to be done.
Handle the case where (not (memq backend backends)).
Don't use vc-resynch-buffer which could lose unsaved editing.
(vc-transfer-file): Docstring fix.

2 files changed, 45 insertions, 15 deletions

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index e13d8a79869..a2be1fe69f9 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,29 @@
+2000-10-01  Stefan Monnier  <monnier@cs.yale.edu>
+
+        * vc.el (vc-editable-p): Minor optimization.
+        (edit-vc-file, vc-next-action-on-file): Don't use find-file.
+        (vc-find-new-backend): New function split from vc-responsible-backend.
+        (vc-register): Use it.
+        (vc-responsible-backend): Remove REGISTER arg and add BACKENDS arg.
+        (vc-unregister): Drop BACKEND arg (it doesn't work anyway).
+        (vc-default-unregister, vc-revert-buffer): Docstring fix.
+        (vc-clear-headers): Don't use find-file.
+        (vc-revert-buffer): Use `and' again (must have been a braino).
+        (vc-switch-backend): Only prompt if requested.
+        Short circuit if nothing is to be done.
+        Don't use vc-resynch-buffer which could lose unsaved editing.
+        (vc-default-receive-file): Update call to vc-unregister.
+        (with-vc-file, vc-next-action-on-file):
+        Use vc-backend rather than vc-registered.
+        (vc-next-action-on-file): Use intern-soft.
+        Deal with read-only *vc-diff* buffer.
+        (vc-transfer-file): Docstring fix.
+
+        * vc-rcs.el (vc-rcs-unregister): Keep a backup of the master file.
+        (vc-rcs-receive-file): Avoid with-vc-properties.
+        Update call to vc-unregister.
+        Use constant `RCS' rather than (dynamically bound) var `backend'.
+
 2000-10-01  Andre Spiegel  <spiegel@gnu.org>
 
         * vc.el (vc-next-action-on-file): Update mode line only if file 
diff --git a/lisp/vc.el b/lisp/vc.el
index 661757c89e9..87a92e0d681 100644
--- a/lisp/vc.el
+++ b/lisp/vc.el
@@ -504,7 +504,7 @@ FILE is passed through `expand-file-name'; BODY executed within
 `save-excursion'.  If FILE is not under version control, or locked by
 somebody else, signal error."
   `(let ((file (expand-file-name ,file)))
-     (or (vc-registered file)
+     (or (vc-backend file)
          (error (format "File not under version control: `%s'" file)))
      (unless (vc-editable-p file)
        (let ((state (vc-state file)))
@@ -833,7 +833,7 @@ If VERBOSE is non-nil, query the user rather than using default parameters."
                 (error "Aborted")))))
     
     ;; Do the right thing
-    (if (not (vc-registered file))
+    (if (not (vc-backend file))
         (vc-register verbose comment)
       (vc-recompute-state file)
       (if visited (vc-mode-line file))
@@ -845,12 +845,12 @@ If VERBOSE is non-nil, query the user rather than using default parameters."
         (cond
          (verbose
           ;; go to a different version
-          (setq version 
+          (setq version
                 (read-string "Branch, version, or backend to move to: "))
-          (let ((vsym (intern (upcase version))))
+          (let ((vsym (intern-soft (upcase version))))
             (if (member vsym vc-handled-backends)
                 (vc-transfer-file file vsym)
-              (vc-checkout file (eq (vc-checkout-model file) 'implicit) 
+              (vc-checkout file (eq (vc-checkout-model file) 'implicit)
                            version))))
          ((not (eq (vc-checkout-model file) 'implicit))
           ;; check the file out
@@ -928,8 +928,9 @@ If VERBOSE is non-nil, query the user rather than using default parameters."
         (if (save-window-excursion
               (vc-version-diff file (vc-workfile-version file) nil)
               (goto-char (point-min))
-              (insert-string (format "Changes to %s since last lock:\n\n"
-                                     file))
+              (let ((inhibit-read-only t))
+                (insert-string
+                 (format "Changes to %s since last lock:\n\n" file)))
               (not (beep))
               (yes-or-no-p (concat "File has unlocked changes.  "
                                    "Claim lock retaining changes? ")))
@@ -2240,7 +2241,7 @@ To get a prompt, use a prefix argument."
         (when (vc-call-backend backend 'registered buffer-file-name)
           (push backend backends)))
       ;; Find the next backend.
-      (let ((def (car (delq backend (memq backend (append backends backends)))))
+      (let ((def (car (delq backend (append (memq backend backends) backends))))
             (others (delete backend backends)))
         (cond
          ((null others) (error "No other backend to switch to"))
@@ -2252,17 +2253,20 @@ To get a prompt, use a prefix argument."
              (mapcar (lambda (b) (list (downcase (symbol-name b)))) backends)
              nil t nil nil (downcase (symbol-name def))))))
        (t def))))))
-  (unless (vc-call-backend backend 'registered file)
-    (error "%s is not registered in %s" file backend))
-  (vc-file-clearprops file)
-  (vc-file-setprop file 'vc-backend backend)
-  (vc-resynch-buffer file t t))
+  (unless (eq backend (vc-backend file))
+    (unless (vc-call-backend backend 'registered file)
+      (error "%s is not registered in %s" file backend))
+    (vc-file-clearprops file)
+    (vc-file-setprop file 'vc-backend backend)
+    ;; Force recomputation of the state
+    (vc-call-backend backend 'registered file)
+    (vc-mode-line file)))
 
 ;;;autoload
 (defun vc-transfer-file (file new-backend)
-  "Transfer FILE to another version control system NEW-BACKEND.  
+  "Transfer FILE to another version control system NEW-BACKEND.
 If NEW-BACKEND has a higher precedence than FILE's current backend
-\(i.e. it comes earlier in vc-handled-backends), then register FILE in
+\(i.e.  it comes earlier in `vc-handled-backends'), then register FILE in
 NEW-BACKEND, using the version number from the current backend as the
 base level.  If NEW-BACKEND has a lower precedence than the current
 backend, then commit all changes that were made under the current