emacs-29 ec172d748f 3/3: Avoid assertion violation due to fill-column indicator face

[Eli Zaretskii]

branch: emacs-29
commit ec172d748f31121ed3d72e53e16fef5ee5f9018d
Author: Eli Zaretskii <eliz@gnu.org>
Commit: Eli Zaretskii <eliz@gnu.org>

    Avoid assertion violation due to fill-column indicator face
    
    * src/xdisp.c (extend_face_to_end_of_line): Use the original
    iterator metrics for the stretch glyph, the one unaffected by the
    'fill-column-indicator' face.  (Bug#60580)
---
 src/xdisp.c | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/src/xdisp.c b/src/xdisp.c
index 6c88846e7a..d2c91e5847 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -23322,8 +23322,9 @@ extend_face_to_end_of_line (struct it *it)
          it->avoid_cursor_p = true;
          it->object = Qnil;
 
-         const int stretch_ascent = (((it->ascent + it->descent)
-                                      * FONT_BASE (font)) / FONT_HEIGHT 
(font));
+         const int stretch_height = it->ascent + it->descent;
+         const int stretch_ascent =
+           (stretch_height * FONT_BASE (font)) / FONT_HEIGHT (font);
 
          if (indicator_column >= 0
              && indicator_column > it->current_x
@@ -23343,8 +23344,7 @@ extend_face_to_end_of_line (struct it *it)
              if (stretch_width > 0)
                {
                  append_stretch_glyph (it, Qnil, stretch_width,
-                                       it->ascent + it->descent,
-                                       stretch_ascent);
+                                       stretch_height, stretch_ascent);
                }
 
              /* Generate the glyph indicator only if
@@ -23352,6 +23352,8 @@ extend_face_to_end_of_line (struct it *it)
              if (it->current_x < indicator_column)
                {
                  const int save_face_id = it->face_id;
+                 const int save_ascent = it->ascent;
+                 const int save_descent = it->descent;
                  it->char_to_display
                    = XFIXNAT (Vdisplay_fill_column_indicator_character);
                  it->face_id
@@ -23359,6 +23361,8 @@ extend_face_to_end_of_line (struct it *it)
                                   0, extend_face_id);
                  PRODUCE_GLYPHS (it);
                  it->face_id = save_face_id;
+                 it->ascent = save_ascent;
+                 it->descent = save_descent;
                }
            }
 
@@ -23372,8 +23376,7 @@ extend_face_to_end_of_line (struct it *it)
                {
                  clear_position (it);
                  append_stretch_glyph (it, Qnil, stretch_width,
-                                       it->ascent + it->descent,
-                                       stretch_ascent);
+                                       stretch_height, stretch_ascent);
                }
            }