Fix compilation of Phonon DS9 backend when Qt is built statically.

qt_plugin_instance() isn't defined in a static build.  Assign a pointer
the shared mutex to static member variable in the backend constructor,
rather than returning it from a static member function.

Task-number:    QTBUG-5207
Reviewed-by:    Justin McPherson

3 files changed, 7 insertions, 6 deletions

diff --git a/src/3rdparty/phonon/ds9/backend.cpp b/src/3rdparty/phonon/ds9/backend.cpp
index 6ed0145..fbc4bdc 100644
--- a/src/3rdparty/phonon/ds9/backend.cpp
+++ b/src/3rdparty/phonon/ds9/backend.cpp
@@ -41,6 +41,8 @@ namespace Phonon
 {
     namespace DS9
     {
+        QMutex *Backend::directShowMutex = 0;
+
         bool Backend::AudioMoniker::operator==(const AudioMoniker &other)
         {
             return other->IsEqual(*this) == S_OK;
@@ -50,6 +52,8 @@ namespace Phonon
         Backend::Backend(QObject *parent, const QVariantList &)
             : QObject(parent)
         {
+            directShowMutex = &m_directShowMutex;
+
             ::CoInitialize(0);
 
             //registering meta types
@@ -62,11 +66,8 @@ namespace Phonon
             m_audioOutputs.clear();
             m_audioEffects.clear();
             ::CoUninitialize();
-        }
 
-        QMutex *Backend::directShowMutex()
-        {
-            return &qobject_cast<Backend*>(qt_plugin_instance())->m_directShowMutex;
+            directShowMutex = 0;
         }
 
         QObject *Backend::createObject(BackendInterface::Class c, QObject *parent, const QList<QVariant> &args)
diff --git a/src/3rdparty/phonon/ds9/backend.h b/src/3rdparty/phonon/ds9/backend.h
index 8b020c2..7c3c109 100644
--- a/src/3rdparty/phonon/ds9/backend.h
+++ b/src/3rdparty/phonon/ds9/backend.h
@@ -64,7 +64,7 @@ namespace Phonon
 
             Filter getAudioOutputFilter(int index) const;
 
-            static QMutex *directShowMutex();
+            static QMutex *directShowMutex;
 
         Q_SIGNALS:
             void objectDescriptionChanged(ObjectDescriptionType);
diff --git a/src/3rdparty/phonon/ds9/mediaobject.cpp b/src/3rdparty/phonon/ds9/mediaobject.cpp
index 250b94a..106a4c8 100644
--- a/src/3rdparty/phonon/ds9/mediaobject.cpp
+++ b/src/3rdparty/phonon/ds9/mediaobject.cpp
@@ -177,7 +177,7 @@ namespace Phonon
 
         void WorkerThread::handleTask()
         {
-            QMutexLocker locker(Backend::directShowMutex());
+            QMutexLocker locker(Backend::directShowMutex);
             {
                 QMutexLocker locker(&m_mutex);
                 if (m_finished || m_queue.isEmpty()) {