Avoid crashes at startup on systems that CANNOT_DUMP

* src/xdisp.c (syms_of_xdisp) <redisplay--inhibit-bidi>: New
boolean variable.
(init_iterator, reseat_to_string)
(Fcurrent_bidi_paragraph_direction)
(Fbidi_find_overridden_directionality): Use
redisplay--inhibit-bidi instead of purify-flag, to determine when
it's safe to reorder bidirectional text.

* lisp/loadup.el (redisplay--inhibit-bidi): Set to t at the
beginning of the file.  Reset to nil when charprop.el is
successfully loaded, or when we are going to dump, whichever
happens last.  (Bug#22975)

1 files changed, 11 insertions, 5 deletions

diff --git a/src/xdisp.c b/src/xdisp.c
index e5ac6504067..ce992d42531 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -2946,7 +2946,7 @@ init_iterator (struct it *it, struct window *w,
          character properties needed for reordering are not yet
          available.  */
       it->bidi_p =
-        NILP (Vpurify_flag)
+        !redisplay__inhibit_bidi
         && !NILP (BVAR (current_buffer, bidi_display_reordering))
         && it->multibyte_p;
 
@@ -6641,7 +6641,7 @@ reseat_to_string (struct it *it, const char *s, Lisp_Object string,
      loading loadup.el, as the necessary character property tables are
      not yet available.  */
   it->bidi_p =
-    NILP (Vpurify_flag)
+    !redisplay__inhibit_bidi
     && !NILP (BVAR (&buffer_defaults, bidi_display_reordering));
 
   if (s == NULL)
@@ -21230,7 +21230,7 @@ See also `bidi-paragraph-direction'.  */)
       || NILP (BVAR (buf, enable_multibyte_characters))
       /* When we are loading loadup.el, the character property tables
          needed for bidi iteration are not yet available.  */
-      || !NILP (Vpurify_flag))
+      || redisplay__inhibit_bidi)
     return Qleft_to_right;
   else if (!NILP (BVAR (buf, bidi_paragraph_direction)))
     return BVAR (buf, bidi_paragraph_direction);
@@ -21354,7 +21354,7 @@ the `bidi-class' property of a character.  */)
           /* When we are loading loadup.el, the character property
              tables needed for bidi iteration are not yet
              available.  */
-          || !NILP (Vpurify_flag))
+          || redisplay__inhibit_bidi)
         return Qnil;
 
       validate_subarray (object, from, to, SCHARS (object), &from_pos, &to_pos);
@@ -21382,7 +21382,7 @@ the `bidi-class' property of a character.  */)
           /* When we are loading loadup.el, the character property
              tables needed for bidi iteration are not yet
              available.  */
-          || !NILP (Vpurify_flag))
+          || redisplay__inhibit_bidi)
         return Qnil;
 
       set_buffer_temp (buf);
@@ -31806,6 +31806,12 @@ display table takes effect; in this case, Emacs does not consult
   DEFVAR_LISP ("redisplay--variables", Vredisplay__variables,
      doc: /* A hash-table of variables changing which triggers a thorough redisplay.  */);
   Vredisplay__variables = Qnil;
+
+  DEFVAR_BOOL ("redisplay--inhibit-bidi", redisplay__inhibit_bidi,
+     doc: /* Non-nil means it is not safe to attempt bidi reordering for display.  */);
+  /* Initialize to t, since we need to disable reordering until
+     loadup.el successfully loads charprop.el.  */
+  redisplay__inhibit_bidi = true;
 }