see https://qt.gitorious.net/qt/qtbase/commit/d3951a5b0f4fe9731d1512668b43f51bd98bd84e
and http://lists.qt-project.org/pipermail/interest/2013-September/008591.html
--- src/corelib/global/qglobal.h.orig   2014-04-10 20:37:11.000000000 +0200
+++ src/corelib/global/qglobal.h        2014-09-08 09:39:10.533187070 +0200
@@ -1721,7 +1721,7 @@
    Avoid "unused parameter" warnings
 */
 
-#if defined(Q_CC_INTEL) && !defined(Q_OS_WIN) || defined(Q_CC_RVCT)
+#if defined(Q_CC_RVCT)
 template <typename T>
 inline void qUnused(T &x) { (void)x; }
 #  define Q_UNUSED(x) qUnused(x);
