ediff-regions-internal can't handle (non-overlapping) regions in the same buffer

[Kevin Rodgers]

I'm working on a way to take advantage of Ediff's fine highlighting
feature within Diff mode buffers.  But calling ediff-regions-internal
programmatically with BUFFER-A the same as BUFFER-B doesn't work,
leaving only the region between BEG-B and END-B highighted.  This is
because ediff-extract-diffs first resets point in both buffers (changing
point in BUFFER-A unintentionally), then builds the diff vector by
moving by lines in each buffer.

The fix is simple, and it allows ediff-regions-internal to work with
non-overlapping regions in the same buffer: Don't set point in each
buffer until necessary:

*** emacs-21.4/lisp/ediff-diff.el~      Wed Jul  3 10:49:40 2002
--- emacs-21.4/lisp/ediff-diff.el       Wed Dec  7 13:34:26 2005
***************
*** 378,388 ****
              (ediff-overlay-start
               (ediff-get-value-according-to-buffer-type 'B bounds))))

!     ;; reset point in buffers A/B/C
!     (ediff-with-current-buffer A-buffer
!       (goto-char (if shift-A shift-A (point-min))))
!     (ediff-with-current-buffer B-buffer
!       (goto-char (if shift-B shift-B (point-min))))
      (if (ediff-buffer-live-p C-buffer)
        (ediff-with-current-buffer C-buffer
          (goto-char (point-min))))
--- 378,384 ----
              (ediff-overlay-start
               (ediff-get-value-according-to-buffer-type 'B bounds))))

!     ;; reset point in buffer C
      (if (ediff-buffer-live-p C-buffer)
        (ediff-with-current-buffer C-buffer
          (goto-char (point-min))))
***************
*** 456,461 ****
--- 452,458 ----
                   c-prev c-end)
           ;; else convert lines to points
           (ediff-with-current-buffer A-buffer
+              (goto-char (if shift-A shift-A (point-min)))
             (forward-line (- a-begin a-prev))
             (setq a-begin-pt (point))
             (forward-line (- a-end a-begin))
***************
*** 462,467 ****
--- 459,465 ----
             (setq a-end-pt (point)
                   a-prev a-end))
           (ediff-with-current-buffer B-buffer
+              (goto-char (if shift-B shift-B (point-min)))
             (forward-line (- b-begin b-prev))
             (setq b-begin-pt (point))
             (forward-line (- b-end b-begin))

Thanks,
--
Kevin