Improve detection of long lines.

* src/buffer.h (struct buffer_text): New field.
(BUF_CHARS_UNCHANGED_MODIFIED, CHARS_UNCHANGED_MODIFIED): New macros.

* src/buffer.c (Fget_buffer_create): Initialize the new field.

* src/xdisp.c (mark_window_display_accurate_1): Set the new field.
(redisplay_window): Use it, together with CHARS_MODIFF, instead of
MODIFF and UNCHANGED_MODIFIED to decide whether to check for long
lines.

* src/pdumper.c (dump_buffer): Dump the new field.

1 files changed, 1 insertions, 0 deletions

diff --git a/src/buffer.c b/src/buffer.c
index 4fd5b2be3e9..d4a0c37bed5 100644
--- a/src/buffer.c
+++ b/src/buffer.c
@@ -597,6 +597,7 @@ even if it is dead.  The return value is never nil.  */)
   set_buffer_intervals (b, NULL);
   BUF_UNCHANGED_MODIFIED (b) = 1;
   BUF_OVERLAY_UNCHANGED_MODIFIED (b) = 1;
+  BUF_CHARS_UNCHANGED_MODIFIED (b) = 1;
   BUF_END_UNCHANGED (b) = 0;
   BUF_BEG_UNCHANGED (b) = 0;
   *(BUF_GPT_ADDR (b)) = *(BUF_Z_ADDR (b)) = 0; /* Put an anchor '\0'.  */