emacs-28 b1e92c59ed: Avoid assertion violations in 'pop_it'

[Eli Zaretskii]

branch: emacs-28
commit b1e92c59ede2e67e36531a35ecb4ccabeaa68ff6
Author: Eli Zaretskii <eliz@gnu.org>
Commit: Eli Zaretskii <eliz@gnu.org>

    Avoid assertion violations in 'pop_it'
    
    * src/xdisp.c (pop_it): Avoid assertion violations when handling
    lists or vectors of display properties.  (Bug#58122)
---
 src/xdisp.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/src/xdisp.c b/src/xdisp.c
index 6d42105474..f5f3a811e9 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -6755,7 +6755,14 @@ pop_it (struct it *it)
               || (STRINGP (it->object)
                   && IT_STRING_CHARPOS (*it) == it->bidi_it.charpos
                   && IT_STRING_BYTEPOS (*it) == it->bidi_it.bytepos)
-              || (CONSP (it->object) && it->method == GET_FROM_STRETCH));
+              || (CONSP (it->object) && it->method == GET_FROM_STRETCH)
+              /* We could be in the middle of handling a list or a
+                 vector of several 'display' properties, in which
+                 case we should only verify the above conditions when
+                 we pop the iterator stack the last time, because
+                 higher stack levels cannot "iterate out of the
+                 display property".  */
+              || it->sp > 0);
     }
   /* If we move the iterator over text covered by a display property
      to a new buffer position, any info about previously seen overlays