1 files changed, 13 insertions, 2 deletions

diff --git a/src/composite.c b/src/composite.c
index 2fbe6796b59..a5288cb8a25 100644
--- a/src/composite.c
+++ b/src/composite.c
@@ -1171,7 +1171,9 @@ composition_compute_stop_pos (struct composition_it *cmp_it, ptrdiff_t charpos,
    character to check, and CHARPOS and BYTEPOS are indices in the
    string.  In that case, FACE must not be NULL.  BIDI_LEVEL is the bidi
    embedding level of the current paragraph, and is used to calculate the
-   direction argument to pass to the font shaper.
+   direction argument to pass to the font shaper; value of -1 means the
+   caller doesn't know the embedding level (used by callers which didn't
+   invoke the display routines that perform bidi-display-reordering).
 
    If the character is composed, setup members of CMP_IT (id, nglyphs,
    from, to, reversed_p), and return true.  Otherwise, update
@@ -1256,7 +1258,16 @@ composition_reseat_it (struct composition_it *cmp_it, ptrdiff_t charpos,
               else
                 bpos = CHAR_TO_BYTE (cpos);
             }
-          if ((bidi_level & 1) == 0)
+          /* The bidi_level < 0 case below strictly speaking should
+             never happen, since we get here when bidi scan direction
+             is backward in the buffer, which can only happen if the
+             display routines were called to perform the bidi
+             reordering.  But it doesn't harm to test for that, and
+             avoid someon raising their brows and thinking it's a
+             subtle bug...  */
+          if (bidi_level < 0)
+            direction = Qnil;
+          else if ((bidi_level & 1) == 0)
             direction = QL2R;
           else
             direction = QR2L;