From: Stefan Monnier <monnier@iro.umontreal.ca>
Date: Tue, 2 Jul 2024 20:28:08 +0000 (-0400)
Subject: (buf_*pos_to_*pos): Fix minor off-by one
X-Git-Url: http://git.eshelyaron.com/gitweb/?a=commitdiff_plain;h=301a6f00db02d39a543660a18dec001cef03e3ee;p=emacs.git

(buf_*pos_to_*pos): Fix minor off-by one

* src/marker.c (buf_charpos_to_bytepos, buf_bytepos_to_charpos):
Slightly restructure the markers loop so we check `distance`
also before "consider"ing the first marker.

(cherry picked from commit 0385c0c0820361b71a74988f23d0445238f30473)
---

diff --git a/src/marker.c b/src/marker.c
index 9aaa2e7402c..16fa3bcef3e 100644
--- a/src/marker.c
+++ b/src/marker.c
@@ -202,19 +202,15 @@ buf_charpos_to_bytepos (struct buffer *b, ptrdiff_t charpos)
   if (b == cached_buffer && BUF_MODIFF (b) == cached_modiff)
     CONSIDER (cached_charpos, cached_bytepos);
 
-  for (tail = BUF_MARKERS (b); tail; tail = tail->next)
-    {
-      CONSIDER (tail->charpos, tail->bytepos);
-
-      /* If we are down to a range of 50 chars,
-	 don't bother checking any other markers;
-	 scan the intervening chars directly now.  */
-      if (best_above - charpos < distance
-          || charpos - best_below < distance)
-	break;
-      else
-        distance += BYTECHAR_DISTANCE_INCREMENT;
-    }
+  for (tail = BUF_MARKERS (b);
+       /* If we are down to a range of DISTANCE chars,
+          don't bother checking any other markers;
+          scan the intervening chars directly now.  */
+       tail && !(best_above - charpos < distance
+		 || charpos - best_below < distance);
+       tail = tail->next,
+       distance += BYTECHAR_DISTANCE_INCREMENT)
+    CONSIDER (tail->charpos, tail->bytepos);
 
   /* We get here if we did not exactly hit one of the known places.
      We have one known above and one known below.
@@ -354,19 +350,15 @@ buf_bytepos_to_charpos (struct buffer *b, ptrdiff_t bytepos)
   if (b == cached_buffer && BUF_MODIFF (b) == cached_modiff)
     CONSIDER (cached_bytepos, cached_charpos);
 
-  for (tail = BUF_MARKERS (b); tail; tail = tail->next)
-    {
-      CONSIDER (tail->bytepos, tail->charpos);
-
-      /* If we are down to a range of DISTANCE bytes,
-	 don't bother checking any other markers;
-	 scan the intervening chars directly now.  */
-      if (best_above_byte - bytepos < distance
-          || bytepos - best_below_byte < distance)
-	break;
-      else
-        distance += BYTECHAR_DISTANCE_INCREMENT;
-    }
+  for (tail = BUF_MARKERS (b);
+       /* If we are down to a range of DISTANCE bytes,
+          don't bother checking any other markers;
+          scan the intervening chars directly now.  */
+       tail && !(best_above_byte - bytepos < distance
+		 || bytepos - best_below_byte < distance);
+       tail = tail->next,
+       distance += BYTECHAR_DISTANCE_INCREMENT)
+    CONSIDER (tail->bytepos, tail->charpos);
 
   /* We get here if we did not exactly hit one of the known places.
      We have one known above and one known below.