Undo in region after markers in undo history relocated

* simple.el (primitive-undo): Only process marker adjustments
validated against their corresponding (TEXT . POS).  Issue warning
for lone marker adjustments in undo history.  (Bug#16818)
(undo-make-selective-list): Add marker adjustments to selective
undo list based on whether their corresponding (TEXT . POS) is in
the region.  Remove variable adjusted-markers, which was unused
and only non nil during undo-make-selective-list.
(undo-elt-in-region): Return nil when passed a marker adjustment
and explain in function doc.

Have (MARKER . ADJUSTMENT) undo records always be immediately
after their corresponding (TEXT . POS) record in undo list.
(Bug#16818)
* lisp.h (record-delete): New arg record_markers.
(record_marker_adjustment): No longer needed outside undo.c.
* insdel.c (adjust_markers_for_delete): Move calculation of marker
adjustments to undo.c's record_marker_adjustments.  Note that
fileio.c's decide_coding_unwind is another caller to
adjust_markers_for_delete.  Because it has undo list bound to t,
it does not rely on adjust_markers_for_delete to record marker
adjustments.
(del_range_2): Swap call to record_delete and
adjust_markers_for_delete so as undo marker adjustments are
recorded before current deletion's adjustments, as before.
(adjust_after_replace):
(replace_range): Pass value for new record_markers arg to
delete_record.
* undo.c (record_marker_adjustment): Renamed to
record_marker_adjustments and made static.
(record_delete): Check record_markers arg and call
record_marker_adjustments.
(record_change): Pass value for new record_markers arg to
delete_record.
(record_point): at_boundary calculation no longer needs to account
for marker adjustments.

* undo-tests.el (undo-test-marker-adjustment-nominal):
(undo-test-region-t-marker): New tests of marker adjustments.
(undo-test-marker-adjustment-moved):
(undo-test-region-mark-adjustment): New tests to demonstrate
bug#16818, which fail without the fix.

* markers.texi (Moving Marker Positions): The 2014-03-02 doc
change mentioning undo's inability to handle relocated markers no
longer applies.  See bug#16818.
* text.texi (Undo): Expand documentation of (TEXT . POS) and
(MARKER . ADJUSTMENT) undo elements.

2 files changed, 106 insertions, 0 deletions

diff --git a/test/ChangeLog b/test/ChangeLog
index 15677e76468..e5df7536d0b 100644
--- a/test/ChangeLog
+++ b/test/ChangeLog
@@ -1,3 +1,11 @@
+2014-03-24  Barry O'Reilly  <gundaetiapo@gmail.com>
+
+	* undo-tests.el (undo-test-marker-adjustment-nominal):
+	(undo-test-region-t-marker): New tests of marker adjustments.
+	(undo-test-marker-adjustment-moved):
+	(undo-test-region-mark-adjustment): New tests to demonstrate
+	bug#16818, which fail without the fix.
+
 2014-03-23  Daniel Colascione  <dancol@dancol.org>
 
 	* automated/cl-lib.el (cl-lib-keyword-names-versus-values): New
diff --git a/test/automated/undo-tests.el b/test/automated/undo-tests.el
index 8a963f10028..6ecac36b6b3 100644
--- a/test/automated/undo-tests.el
+++ b/test/automated/undo-tests.el
@@ -268,6 +268,104 @@
     (should (string= (buffer-string)
                      "This sentence corrupted?aaa"))))
 
+(ert-deftest undo-test-marker-adjustment-nominal ()
+  "Test nominal behavior of marker adjustments."
+  (with-temp-buffer
+    (buffer-enable-undo)
+    (insert "abcdefg")
+    (undo-boundary)
+    (let ((m (make-marker)))
+      (set-marker m 2 (current-buffer))
+      (goto-char (point-min))
+      (delete-forward-char 3)
+      (undo-boundary)
+      (should (= (point-min) (marker-position m)))
+      (undo)
+      (undo-boundary)
+      (should (= 2 (marker-position m))))))
+
+(ert-deftest undo-test-region-t-marker ()
+  "Test undo in region containing marker with t insertion-type."
+  (with-temp-buffer
+    (buffer-enable-undo)
+    (transient-mark-mode 1)
+    (insert "abcdefg")
+    (undo-boundary)
+    (let ((m (make-marker)))
+      (set-marker-insertion-type m t)
+      (set-marker m (point-min) (current-buffer)) ; m at a
+      (goto-char (+ 2 (point-min)))
+      (push-mark (point) t t)
+      (setq mark-active t)
+      (goto-char (point-min))
+      (delete-forward-char 1) ;; delete region covering "ab"
+      (undo-boundary)
+      (should (= (point-min) (marker-position m)))
+      ;; Resurrect "ab". m's insertion type means the reinsertion
+      ;; moves it forward 2, and then the marker adjustment returns it
+      ;; to its rightful place.
+      (undo)
+      (undo-boundary)
+      (should (= (point-min) (marker-position m))))))
+
+(ert-deftest undo-test-marker-adjustment-moved ()
+  "Test marker adjustment behavior when the marker moves.
+Demonstrates bug 16818."
+  (with-temp-buffer
+    (buffer-enable-undo)
+    (insert "abcdefghijk")
+    (undo-boundary)
+    (let ((m (make-marker)))
+      (set-marker m 2 (current-buffer)) ; m at b
+      (goto-char (point-min))
+      (delete-forward-char 3) ; m at d
+      (undo-boundary)
+      (set-marker m 4) ; m at g
+      (undo)
+      (undo-boundary)
+      ;; m still at g, but shifted 3 because deletion undone
+      (should (= 7 (marker-position m))))))
+
+(ert-deftest undo-test-region-mark-adjustment ()
+  "Test that the mark's marker adjustment in undo history doesn't
+obstruct undo in region from finding the correct change group.
+Demonstrates bug 16818."
+  (with-temp-buffer
+    (buffer-enable-undo)
+    (transient-mark-mode 1)
+    (insert "First line\n")
+    (insert "Second line\n")
+    (undo-boundary)
+
+    (goto-char (point-min))
+    (insert "aaa")
+    (undo-boundary)
+
+    (undo)
+    (undo-boundary)
+
+    (goto-char (point-max))
+    (insert "bbb")
+    (undo-boundary)
+
+    (push-mark (point) t t)
+    (setq mark-active t)
+    (goto-char (- (point) 3))
+    (delete-forward-char 1)
+    (undo-boundary)
+
+    (insert "bbb")
+    (undo-boundary)
+
+    (goto-char (point-min))
+    (push-mark (point) t t)
+    (setq mark-active t)
+    (goto-char (+ (point) 3))
+    (undo)
+    (undo-boundary)
+
+    (should (string= (buffer-string) "aaaFirst line\nSecond line\nbbb"))))
+
 (defun undo-test-all (&optional interactive)
   "Run all tests for \\[undo]."
   (interactive "p")