1 files changed, 21 insertions, 0 deletions
diff --git a/thirdparty/harfbuzz/src/hb-ot-shape-complex-arabic.cc b/thirdparty/harfbuzz/src/hb-ot-shape-complex-arabic.cc
index 222c5d6b71..2298aa92f2 100644
--- a/thirdparty/harfbuzz/src/hb-ot-shape-complex-arabic.cc
+++ b/thirdparty/harfbuzz/src/hb-ot-shape-complex-arabic.cc
@@ -321,6 +321,20 @@ arabic_joining (hb_buffer_t *buffer)
       info[prev].arabic_shaping_action() = entry->prev_action;
       buffer->unsafe_to_break (prev, i + 1);
     }
+    else
+    {
+      if (prev == UINT_MAX)
+      {
+        if (this_type >= JOINING_TYPE_R)
+	  buffer->unsafe_to_concat_from_outbuffer (0, i + 1);
+      }
+      else
+      {
+	if (this_type >= JOINING_TYPE_R ||
+	    (2 <= state && state <= 5) /* States that have a possible prev_action. */)
+	  buffer->unsafe_to_concat (prev, i + 1);
+      }
+    }
 
     info[i].arabic_shaping_action() = entry->curr_action;
 
@@ -337,7 +351,14 @@ arabic_joining (hb_buffer_t *buffer)
 
     const arabic_state_table_entry *entry = &arabic_state_table[state][this_type];
     if (entry->prev_action != NONE && prev != UINT_MAX)
+    {
       info[prev].arabic_shaping_action() = entry->prev_action;
+      buffer->unsafe_to_break (prev, buffer->len);
+    }
+    else if (2 <= state && state <= 5) /* States that have a possible prev_action. */
+    {
+      buffer->unsafe_to_concat (prev, buffer->len);
+    }
     break;
   }
 }