Fix display of empty margins when default face is remapped

* src/xdisp.c (display_line): Append space glyphs to margin areas
if the default face is remapped and nothing is written to the
margin area of this screen line.
(produce_special_glyphs): If the truncation/continuation glyphs do
not specify a face, use the remapped default face, not the
original frame-global default face.  Reported by Nicolas
P. Rougier <nicolas.rougier@inria.fr> in
https://lists.gnu.org/archive/html/emacs-devel/2024-07/msg01217.html.

1 files changed, 19 insertions, 5 deletions

diff --git a/src/xdisp.c b/src/xdisp.c
index a8f9f59b654..491ce9cc970 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -25961,6 +25961,18 @@ display_line (struct it *it, int cursor_vpos)
                     }
                   it->hpos = hpos_before;
                 }
+              /* If the default face is remapped, and the window has
+                 display margins, and no glyphs were written yet to the
+                 margins on this screen line, we must add one space
+                 glyph to the margin area to make sure the margins use
+                 the background of the remapped default face.  */
+              if (lookup_basic_face (it->w, it->f, DEFAULT_FACE_ID)
+                  != DEFAULT_FACE_ID /* default face is remapped */
+                  && ((WINDOW_LEFT_MARGIN_WIDTH (it->w) > 0
+                       && it->glyph_row->used[LEFT_MARGIN_AREA] == 0)
+                      || (WINDOW_RIGHT_MARGIN_WIDTH (it->w) > 0
+                          && it->glyph_row->used[RIGHT_MARGIN_AREA] == 0)))
+                extend_face_to_end_of_line (it);
             }
           else if (IT_OVERFLOW_NEWLINE_INTO_FRINGE (it))
             {
@@ -32179,6 +32191,8 @@ produce_special_glyphs (struct it *it, enum display_element_type what)
   struct it temp_it;
   Lisp_Object gc;
   GLYPH glyph;
+  /* Take face-remapping into consideration.  */
+  int face_id = lookup_basic_face (it->w, it->f, DEFAULT_FACE_ID);
 
   temp_it = *it;
   temp_it.object = Qnil;
@@ -32188,27 +32202,27 @@ produce_special_glyphs (struct it *it, enum display_element_type what)
     {
       /* Continuation glyph.  For R2L lines, we mirror it by hand.  */
       if (it->bidi_it.paragraph_dir == R2L)
-        SET_GLYPH_FROM_CHAR (glyph, '/');
+        SET_GLYPH (glyph, '/', face_id);
       else
-        SET_GLYPH_FROM_CHAR (glyph, '\\');
+        SET_GLYPH (glyph, '\\', face_id);
       if (it->dp
           && (gc = DISP_CONTINUE_GLYPH (it->dp), GLYPH_CODE_P (gc)))
         {
           /* FIXME: Should we mirror GC for R2L lines?  */
           SET_GLYPH_FROM_GLYPH_CODE (glyph, gc);
-          spec_glyph_lookup_face (XWINDOW (it->window), &glyph);
+          spec_glyph_lookup_face (it->w, &glyph);
         }
     }
   else if (what == IT_TRUNCATION)
     {
       /* Truncation glyph.  */
-      SET_GLYPH_FROM_CHAR (glyph, '$');
+      SET_GLYPH (glyph, '$', face_id);
       if (it->dp
           && (gc = DISP_TRUNC_GLYPH (it->dp), GLYPH_CODE_P (gc)))
         {
           /* FIXME: Should we mirror GC for R2L lines?  */
           SET_GLYPH_FROM_GLYPH_CODE (glyph, gc);
-          spec_glyph_lookup_face (XWINDOW (it->window), &glyph);
+          spec_glyph_lookup_face (it->w, &glyph);
         }
     }
   else