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.

1 files changed, 8 insertions, 32 deletions

diff --git a/src/insdel.c b/src/insdel.c
index 1c9bafd6004..eb1ad627f66 100644
--- a/src/insdel.c
+++ b/src/insdel.c
@@ -233,34 +233,9 @@ adjust_markers_for_delete (ptrdiff_t from, ptrdiff_t from_byte,
       /* Here's the case where a marker is inside text being deleted.  */
       else if (charpos > from)
 	{
-	  if (! m->insertion_type)
-	    { /* Normal markers will end up at the beginning of the
-	       re-inserted text after undoing a deletion, and must be
-	       adjusted to move them to the correct place.  */
-	      XSETMISC (marker, m);
-	      record_marker_adjustment (marker, from - charpos);
-	    }
-	  else if (charpos < to)
-	    { /* Before-insertion markers will automatically move forward
-	       upon re-inserting the deleted text, so we have to arrange
-	       for them to move backward to the correct position.  */
-	      XSETMISC (marker, m);
-	      record_marker_adjustment (marker, to - charpos);
-	    }
 	  m->charpos = from;
 	  m->bytepos = from_byte;
 	}
-      /* Here's the case where a before-insertion marker is immediately
-	 before the deleted region.  */
-      else if (charpos == from && m->insertion_type)
-	{
-	  /* Undoing the change uses normal insertion, which will
-	     incorrectly make MARKER move forward, so we arrange for it
-	     to then move backward to the correct place at the beginning
-	     of the deleted region.  */
-	  XSETMISC (marker, m);
-	  record_marker_adjustment (marker, to - from);
-	}
     }
 }
 
@@ -1219,7 +1194,7 @@ adjust_after_replace (ptrdiff_t from, ptrdiff_t from_byte,
 			       from + len, from_byte + len_byte, 0);
 
   if (nchars_del > 0)
-    record_delete (from, prev_text);
+    record_delete (from, prev_text, false);
   record_insert (from, len);
 
   if (len > nchars_del)
@@ -1384,7 +1359,7 @@ replace_range (ptrdiff_t from, ptrdiff_t to, Lisp_Object new,
   if (!NILP (deletion))
     {
       record_insert (from + SCHARS (deletion), inschars);
-      record_delete (from, deletion);
+      record_delete (from, deletion, false);
     }
 
   GAP_SIZE -= outgoing_insbytes;
@@ -1716,13 +1691,14 @@ del_range_2 (ptrdiff_t from, ptrdiff_t from_byte,
   else
     deletion = Qnil;
 
-  /* Relocate all markers pointing into the new, larger gap
-     to point at the end of the text before the gap.
-     Do this before recording the deletion,
-     so that undo handles this after reinserting the text.  */
+  /* Record marker adjustments, and text deletion into undo
+     history.  */
+  record_delete (from, deletion, true);
+
+  /* Relocate all markers pointing into the new, larger gap to point
+     at the end of the text before the gap.  */
   adjust_markers_for_delete (from, from_byte, to, to_byte);
 
-  record_delete (from, deletion);
   MODIFF++;
   CHARS_MODIFF = MODIFF;