From c55c01977101f999145594b950d4ea802e723ce7 Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Mon, 21 Mar 2022 19:11:17 -0600
Subject: [PATCH] [buffer] Add assertions of buffer sync status to message_impl

---
 src/hb-buffer.cc | 10 +++++++++-
 src/hb-buffer.hh |  4 ----
 2 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/src/hb-buffer.cc b/src/hb-buffer.cc
index e09dee77f..83cd3dca8 100644
--- a/src/hb-buffer.cc
+++ b/src/hb-buffer.cc
@@ -2116,8 +2116,16 @@ hb_buffer_set_message_func (hb_buffer_t *buffer,
 bool
 hb_buffer_t::message_impl (hb_font_t *font, const char *fmt, va_list ap)
 {
+  assert (!have_output || (out_info == info && out_len == idx));
+
+  message_depth++;
+
   char buf[100];
   vsnprintf (buf, sizeof (buf), fmt, ap);
-  return (bool) this->message_func (this, font, buf, this->message_data);
+  bool ret = (bool) this->message_func (this, font, buf, this->message_data);
+
+  message_depth--;
+
+  return ret;
 }
 #endif
diff --git a/src/hb-buffer.hh b/src/hb-buffer.hh
index 5ad273ce8..1b89a32db 100644
--- a/src/hb-buffer.hh
+++ b/src/hb-buffer.hh
@@ -556,15 +556,11 @@ struct hb_buffer_t
     if (likely (!messaging ()))
       return true;
 
-    message_depth++;
-
     va_list ap;
     va_start (ap, fmt);
     bool ret = message_impl (font, fmt, ap);
     va_end (ap);
 
-    message_depth--;
-
     return ret;
 #endif
   }