vc-ediff

vc-ediff is an interactive autoloaded compiled Lisp function in `vc.el'.


(vc-ediff HISTORIC &optional NOT-URGENT)

Display diffs between file revisions using ediff.
Normally this compares the currently selected fileset with their
working revisions. With a prefix argument HISTORIC, it reads two revision
designators specifying which revisions to compare.

The optional argument NOT-URGENT non-nil means it is ok to say no to
saving the buffer.