Add QThreadStorage stub implementation

Add implementation for the no-thread configuration:
Assume access will only happen from one thread and
use a QScopedPointer to hold the data.

Unlike the real implementation this version will
delete the stored data on destruction, as opposed
to on QApplication destruction.

Change-Id: I9d8e89e7da18f967f463e2db7b50549c962acc84
Reviewed-by: Lorn Potter <lorn.potter@gmail.com>

src/corelib/thread/qthreadstorage.h

@@ -152,6 +152,81 @@ public:
 
 QT_END_NAMESPACE
 
+#else // !QT_NO_THREAD
+
+#include <qscopedpointer.h>
+
+#include <type_traits>
+
+template <typename T, typename U>
+inline bool qThreadStorage_hasLocalData(const QScopedPointer<T, U> &data)
+{
+    return !!data;
+}
+
+template <typename T, typename U>
+inline bool qThreadStorage_hasLocalData(const QScopedPointer<T*, U> &data)
+{
+    return !!data ? *data != nullptr : false;
+}
+
+template <typename T>
+inline void qThreadStorage_deleteLocalData(T *t)
+{
+    delete t;
+}
+
+template <typename T>
+inline void qThreadStorage_deleteLocalData(T **t)
+{
+    delete *t;
+    delete t;
+}
+
+template <class T>
+class QThreadStorage
+{
+private:
+    struct ScopedPointerThreadStorageDeleter
+    {
+        static inline void cleanup(T *t)
+        {
+            if (t == nullptr)
+                return;
+            qThreadStorage_deleteLocalData(t);
+        }
+    };
+    QScopedPointer<T, ScopedPointerThreadStorageDeleter> data;
+
+public:
+    QThreadStorage() = default;
+    ~QThreadStorage() = default;
+    QThreadStorage(const QThreadStorage &rhs) = delete;
+    QThreadStorage &operator=(const QThreadStorage &rhs) = delete;
+
+    inline bool hasLocalData() const
+    {
+        return qThreadStorage_hasLocalData(data);
+    }
+
+    inline T& localData()
+    {
+        if (!data)
+            data.reset(new T());
+        return *data;
+    }
+
+    inline T localData() const
+    {
+        return !!data ? *data : T();
+    }
+
+    inline void setLocalData(T t)
+    {
+        data.reset(new T(t));
+    }
+};
+
 #endif // QT_NO_THREAD
 
 #endif // QTHREADSTORAGE_H