[gpos] Break cycle-of-2 when cursive attaching

Fixes https://github.com/harfbuzz/harfbuzz/issues/2469
2020-06-17 17:41:15 -07:00 · 2020-06-17 17:41:15 -07:00 · 7090707de6
parent 09dedb1b38
commit 7090707de6
1 changed files with 6 additions and 0 deletions
--- a/src/hb-ot-layout-gpos-table.hh
+++ b/src/hb-ot-layout-gpos-table.hh
@ -1692,6 +1692,12 @@ struct CursivePosFormat1
    else
      pos[child].x_offset = x_offset;

+    /* If parent was attached to child, break them free.
+     * https://github.com/harfbuzz/harfbuzz/issues/2469
+     */
+    if (unlikely (pos[parent].attach_chain() = -pos[child].attach_chain()))
+      pos[parent].attach_chain() = 0;
+
    buffer->idx++;
    return_trace (true);
  }