Maintain interval ->position fields correctly in update_interval

Also fix some anomalies in the handling of byte positions in regexp-emacs.c
This fixes bug #34525.

* src/intervals.c (SET_PARENT_POSITION): New macro.
(update_interval): When moving to an interval's parent, set that parent's
->position field, to maintain the consistency of the tree.

* src/intervals.h (struct interval): Amend the comment describing when
->position is valid.

* src/pdumper.c: Update the hash associated with struct interval.

* src/regex-emacs.c: (re_match_2_internal): Only invoke POINTER_TO_OFFSET on a
known character boundary.  Only perform arithmetic on character positions, not
on byte positions.  Correct the argument to an invocation of
UPDATE_SYNTAX_TABLE_FORWARD by adding 1 to it (in case wordend:).

* src/syntax.c: (update_syntax_table): Remove the now redundant code that set
the ->position field of all parents of the interval found by update_interval.

1 files changed, 9 insertions, 5 deletions

diff --git a/src/intervals.h b/src/intervals.h
index 9c5adf33a14..e9166946d9a 100644
--- a/src/intervals.h
+++ b/src/intervals.h
@@ -31,11 +31,15 @@ struct interval
   /* The first group of entries deal with the tree structure.  */
   ptrdiff_t total_length;       /* Length of myself and both children.  */
   ptrdiff_t position;	        /* Cache of interval's character position.  */
-				/* This field is usually updated
-				   simultaneously with an interval
-				   traversal, there is no guarantee
-				   that it is valid for a random
-				   interval.  */
+                                /* This field is valid in the final
+                                   target interval returned by
+                                   find_interval, next_interval,
+                                   previous_interval and
+                                   update_interval.  It cannot be
+                                   depended upon in any intermediate
+                                   intervals traversed by these
+                                   functions, or any other
+                                   interval. */
   struct interval *left;	/* Intervals which precede me.  */
   struct interval *right;	/* Intervals which succeed me.  */