Discard changes to buffer->clip_changed incurred during fontification.

* src/xdisp.c (handle_fontified_prop): Discard changes to clip_changed
incurred during fontification.

2 files changed, 25 insertions, 0 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index bd06cd1869e..c7b0edede3f 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,8 @@
+2011-03-25  Chong Yidong  <cyd@stupidchicken.com>
+
+        * xdisp.c (handle_fontified_prop): Discard changes to clip_changed
+        incurred during fontification.
+
 2011-03-25  Juanma Barranquero  <lekktu@gmail.com>
 
         * buffer.c (defvar_per_buffer): Remove unused parameter `doc'.
diff --git a/src/xdisp.c b/src/xdisp.c
index 457a5e3e11b..cc5d61abdb2 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -3164,6 +3164,9 @@ handle_fontified_prop (struct it *it)
     {
       int count = SPECPDL_INDEX ();
       Lisp_Object val;
+      struct buffer *obuf = current_buffer;
+      int begv = BEGV, zv = ZV;
+      int old_clip_changed = current_buffer->clip_changed;
 
       val = Vfontification_functions;
       specbind (Qfontification_functions, Qnil);
@@ -3209,6 +3212,23 @@ handle_fontified_prop (struct it *it)
 
       unbind_to (count, Qnil);
 
+      /* Fontification functions routinely call `save-restriction'.
+         Normally, this tags clip_changed, which can confuse redisplay
+         (see discussion in Bug#6671).  Since we don't perform any
+         special handling of fontification changes in the case where
+         `save-restriction' isn't called, there's no point doing so in
+         this case either.  So, if the buffer's restrictions are
+         actually left unchanged, reset clip_changed.  */
+      if (obuf == current_buffer)
+        {
+          if (begv == BEGV && zv == ZV)
+            current_buffer->clip_changed = old_clip_changed;
+        }
+      /* There isn't much we can reasonably do to protect against
+         misbehaving fontification, but here's a fig leaf.  */
+      else if (!NILP (BVAR (obuf, name)))
+        set_buffer_internal_1 (obuf);
+
       /* The fontification code may have added/removed text.
          It could do even a lot worse, but let's at least protect against
          the most obvious case where only the text past `pos' gets changed',