In C-x v L and C-x v D, prompt for directory if there is no default backend.

* lisp/vc/vc.el (vc-root-diff, vc-print-root-log): Prompt for a
directory if vc-deduce-backend returns nil.

Fixes: debbugs:7350

2 files changed, 19 insertions, 6 deletions

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index d8e8575db89..f31218506ba 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -12,6 +12,9 @@
 
 2012-07-28  Chong Yidong  <cyd@gnu.org>
 
+        * vc/vc.el (vc-root-diff, vc-print-root-log): Prompt for a
+        directory if vc-deduce-backend returns nil (Bug#7350).
+
         * simple.el (delete-trailing-lines): New option.
         (delete-trailing-whitespace): Obey it (Bug#11879).
 
diff --git a/lisp/vc/vc.el b/lisp/vc/vc.el
index 0f3298d2686..2d95b14244f 100644
--- a/lisp/vc/vc.el
+++ b/lisp/vc/vc.el
@@ -1757,10 +1757,15 @@ saving the buffer."
       (call-interactively 'vc-version-diff)
     (when buffer-file-name (vc-buffer-sync not-urgent))
     (let ((backend (vc-deduce-backend))
+          (default-directory default-directory)
           rootdir working-revision)
-      (unless backend
-        (error "Buffer is not version controlled"))
-      (setq rootdir (vc-call-backend backend 'root default-directory))
+      (if backend
+          (setq rootdir (vc-call-backend backend 'root default-directory))
+        (setq rootdir (read-directory-name "Directory for VC root-diff: "))
+        (setq backend (vc-responsible-backend rootdir))
+        (if backend
+            (setq default-directory rootdir)
+          (error "Directory is not version controlled")))
       (setq working-revision (vc-working-revision rootdir))
       ;; VC diff for the root directory produces output that is
       ;; relative to it.  Bind default-directory to the root directory
@@ -2213,10 +2218,15 @@ When called interactively with a prefix argument, prompt for LIMIT."
     (t
      (list (when (> vc-log-show-limit 0) vc-log-show-limit)))))
   (let ((backend (vc-deduce-backend))
+        (default-directory default-directory)
         rootdir working-revision)
-    (unless backend
-      (error "Buffer is not version controlled"))
-    (setq rootdir (vc-call-backend backend 'root default-directory))
+    (if backend
+        (setq rootdir (vc-call-backend backend 'root default-directory))
+      (setq rootdir (read-directory-name "Directory for VC root-log: "))
+      (setq backend (vc-responsible-backend rootdir))
+      (if backend
+          (setq default-directory rootdir)
+        (error "Directory is not version controlled")))
     (setq working-revision (vc-working-revision rootdir))
     (vc-print-log-internal backend (list rootdir) working-revision nil limit)))