From: Eli Zaretskii <eliz@gnu.org>
Date: Thu, 8 Oct 2020 11:45:16 +0000 (+0300)
Subject: Fix current-line hscrolling when overlays change
X-Git-Tag: emacs-27.1.90~111
X-Git-Url: http://git.eshelyaron.com/gitweb/?a=commitdiff_plain;h=040dcbe53e39a83fde9cbd09e47b6cfe575d2d52;p=emacs.git

Fix current-line hscrolling when overlays change

* src/xdisp.c (redisplay_internal): Disable "optimization 1" when
auto-hscrolling current line and we're redisplaying the selected
window.  (Bug#43835)
---

diff --git a/src/xdisp.c b/src/xdisp.c
index 05f69b0321f..6c401d0abb9 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -15581,7 +15581,12 @@ redisplay_internal (void)
 	      && CHARPOS (this_line_end_pos) == CHARPOS (tlendpos)
               /* Line has same height as before.  Otherwise other lines
                  would have to be shifted up or down.  */
-	      && this_line_pixel_height == line_height_before)
+	      && this_line_pixel_height == line_height_before
+	      /* Cannot use this optimization if hscrolling current
+		 line and this line is the current one, because
+		 display_line above is not informed about the
+		 current-line's vpos, and cannot DTRT in that case.  */
+	      && !hscrolling_current_line_p (w))
 	    {
  	      /* If this is not the window's last line, we must adjust
  		 the charstarts of the lines below.  */