Fix aborts when the value of a display property causes redisplay

* src/xdisp.c (handle_single_display_spec): Protect the bidi
cache from evaluation that triggers redisplay.  (Bug#36312)

1 files changed, 9 insertions, 0 deletions

diff --git a/src/xdisp.c b/src/xdisp.c
index 945174e09c5..5d70440f1cb 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -5000,6 +5000,7 @@ handle_single_display_spec (struct it *it, Lisp_Object spec, Lisp_Object object,
   Lisp_Object form;
   Lisp_Object location, value;
   struct text_pos start_pos = *position;
+  void *itdata = NULL;
 
   /* If SPEC is a list of the form `(when FORM . VALUE)', evaluate FORM.
      If the result is non-nil, use VALUE instead of SPEC.  */
@@ -5029,7 +5030,11 @@ handle_single_display_spec (struct it *it, Lisp_Object spec, Lisp_Object object,
       specbind (Qobject, object);
       specbind (Qposition, make_fixnum (CHARPOS (*position)));
       specbind (Qbuffer_position, make_fixnum (bufpos));
+      /* Save and restore the bidi cache, since FORM could be crazy
+         enough to re-enter redisplay, e.g., by calling 'message'.  */
+      itdata = bidi_shelve_cache ();
       form = safe_eval (form);
+      bidi_unshelve_cache (itdata, false);
       form = unbind_to (count, form);
     }
 
@@ -5069,8 +5074,10 @@ handle_single_display_spec (struct it *it, Lisp_Object spec, Lisp_Object object,
                      Value is the new height.  */
                   struct face *face = FACE_FROM_ID (it->f, it->face_id);
                   Lisp_Object height;
+                  itdata = bidi_shelve_cache ();
                   height = safe_call1 (it->font_height,
                                        face->lface[LFACE_HEIGHT_INDEX]);
+                  bidi_unshelve_cache (itdata, false);
                   if (NUMBERP (height))
                     new_height = XFLOATINT (height);
                 }
@@ -5092,7 +5099,9 @@ handle_single_display_spec (struct it *it, Lisp_Object spec, Lisp_Object object,
                   struct face *face = FACE_FROM_ID (it->f, it->face_id);
 
                   specbind (Qheight, face->lface[LFACE_HEIGHT_INDEX]);
+                  itdata = bidi_shelve_cache ();
                   value = safe_eval (it->font_height);
+                  bidi_unshelve_cache (itdata, false);
                   value = unbind_to (count, value);
 
                   if (NUMBERP (value))