From 140552cec98684cdab72a29ee59ba6ddfcca75b4 Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Fri, 9 Oct 2020 18:01:32 -0600
Subject: [PATCH] [buffer/serialize] Only serialize empty buffers of
 CONTENT_TYPE_INVALID

---
 src/hb-buffer-serialize.cc | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/hb-buffer-serialize.cc b/src/hb-buffer-serialize.cc
index aac2eb10d..b4200354f 100644
--- a/src/hb-buffer-serialize.cc
+++ b/src/hb-buffer-serialize.cc
@@ -605,6 +605,8 @@ _hb_buffer_serialize_invalid (hb_buffer_t *buffer,
                               hb_buffer_serialize_format_t format,
                               hb_buffer_serialize_flags_t flags)
 {
+  assert (!buffer->len);
+
   unsigned int sconsumed;
   if (!buf_consumed)
     buf_consumed = &sconsumed;