emacs-29 d292d282292: Fix rare crashes in 'try_window_reusing_current_matrix'

[Eli Zaretskii]

branch: emacs-29
commit d292d282292b8ce1f4e1ba97d0110178153f73c5
Author: Eli Zaretskii <eliz@gnu.org>
Commit: Eli Zaretskii <eliz@gnu.org>

    Fix rare crashes in 'try_window_reusing_current_matrix'
    
    * src/xdisp.c (try_window_reusing_current_matrix): Make sure we
    never use a mode-line glyph row to start displaying scrolled-in
    rows.  (Bug#63711)
---
 src/xdisp.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/xdisp.c b/src/xdisp.c
index aeba47e4c16..2ddfdf0d51b 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -21081,8 +21081,10 @@ try_window_reusing_current_matrix (struct window *w)
            pt_row = first_row_to_display;
        }
 
+      if (first_row_to_display->y >= yb)
+       return false;
+
       /* Start displaying at the start of first_row_to_display.  */
-      eassert (first_row_to_display->y < yb);
       init_to_row_start (&it, w, first_row_to_display);
 
       nrows_scrolled = (MATRIX_ROW_VPOS (first_reusable_row, w->current_matrix)