From a4b3fc4121fba63307edfd2bce78a4994fbe7ef0 Mon Sep 17 00:00:00 2001
From: Marc Mutz <marc.mutz@qt.io>
Date: Mon, 18 Jul 2022 09:28:20 +0200
Subject: [PATCH] QByteDataBuffer: assert an undocumented precondition

The alternative would be to return a null QByteArray, but the current
implementation makes calling read() on an empty QByteDataBuffer UB, so
this is behavior-preserving, just with a bit nicer error message.

Change-Id: Ia9db7acbfa47e601b466d6cc6a728859065c27b5
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>
Reviewed-by: Sona Kurazyan <sona.kurazyan@qt.io>
(cherry picked from commit 011b68d3cd95295890b1ed724aa4331ff5680eed)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>
---
 src/corelib/text/qbytedata_p.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/corelib/text/qbytedata_p.h b/src/corelib/text/qbytedata_p.h
index 946f9155ffd..46eee13ccd4 100644
--- a/src/corelib/text/qbytedata_p.h
+++ b/src/corelib/text/qbytedata_p.h
@@ -105,6 +105,7 @@ public:
     // preferably use this function to read data.
     inline QByteArray read()
     {
+        Q_ASSERT(!isEmpty());
         squeezeFirst();
         bufferCompleteSize -= buffers.first().size();
         return buffers.takeFirst();