[GSUB] Fix reverse lookup loop like we did in the old code before

diff --git a/src/hb-ot-layout-gsub-private.h b/src/hb-ot-layout-gsub-private.h
index 968dd4a..b607ca5 100644 (file)
--- a/src/hb-ot-layout-gsub-private.h
+++ b/src/hb-ot-layout-gsub-private.h
@@ -808,7 +808,7 @@ struct SubstLookup : Lookup {
          else
            buffer->in_pos--;
 
-       } while (buffer->in_pos);
+       } while ((int) buffer->in_pos >= 0);
     }
 
     return ret;