Avoid unlock/lock dance before waitForNextMessage

Change-Id: I63f2c01b3ca28b0703be6af80f8f7e757948a852
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>

src/qml/qml/ftw/qqmlthread.cpp

@@ -365,6 +365,7 @@ void QQmlThread::internalPostMethodToMain(Message *message)
 /*!
     \internal
     \note This method must be called in the main thread
+    \warning This method requires that the lock is held!
 
     A call to this method will either:
     - run a message requested to run synchronously on the main thread if there is one
@@ -377,7 +378,6 @@ void QQmlThread::waitForNextMessage()
 #if QT_CONFIG(thread)
     Q_ASSERT(!isThisThread());
 #endif
-    d->lock();
     Q_ASSERT(d->m_mainThreadWaiting == false);
 
     d->m_mainThreadWaiting = true;
@@ -397,7 +397,6 @@ void QQmlThread::waitForNextMessage()
     }
 
     d->m_mainThreadWaiting = false;
-    d->unlock();
 }
 
 

src/qml/qml/qqmltypeloader.cpp

@@ -179,9 +179,7 @@ void QQmlTypeLoader::doLoad(const Loader &loader, QQmlDataBlob *blob, Mode mode)
         } else {
             Q_ASSERT(mode == Synchronous);
             while (!blob->isCompleteOrError()) {
-                unlock();
                 m_thread->waitForNextMessage();
-                lock();
             }
         }
     }
@@ -908,9 +906,7 @@ QQmlRefPointer<QQmlTypeData> QQmlTypeLoader::getType(const QUrl &unNormalizedUrl
             // when recursively called on the QML thread via resolveTypes()
 
             while (!typeData->isCompleteOrError()) {
-                unlock();
                 m_thread->waitForNextMessage();
-                lock();
             }
         }
     }