From 56962604254a31d5d54ea41044a5c251ff27fa0c Mon Sep 17 00:00:00 2001
From: Marc Mutz <marc.mutz@kdab.com>
Date: Wed, 26 Jun 2019 17:41:59 +0200
Subject: [PATCH] QObject: fix allocation of IDs for the undocumented
 userData() feature

This appears to have come to some fame on the internet, so better fix
the implementation before we remove it in Qt 6.

Change-Id: Ia37ca89105b13bea1ffcdce8b2e8cd957b7bd108
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
---
 src/corelib/kernel/qobject.cpp | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/src/corelib/kernel/qobject.cpp b/src/corelib/kernel/qobject.cpp
index 9a2ae36177c..69556ba9e31 100644
--- a/src/corelib/kernel/qobject.cpp
+++ b/src/corelib/kernel/qobject.cpp
@@ -4187,13 +4187,14 @@ void QObject::dumpObjectInfo() const
 }
 
 #ifndef QT_NO_USERDATA
+static QBasicAtomicInteger<uint> user_data_registration = Q_BASIC_ATOMIC_INITIALIZER(0);
+
 /*!
     \internal
  */
 uint QObject::registerUserData()
 {
-    static int user_data_registration = 0;
-    return user_data_registration++;
+    return user_data_registration.fetchAndAddRelaxed(1);
 }
 
 /*!