Although this was fixed in 5.6.0, in QT 5.7.0-beta, in Release (not Debug), the following warnings appear for every QMap.h included.

\qtcore\qmap.h(133): warning C4718:
'QMapNode<Cms::Private::ConstCharPointerKey,ComponentConstructorBase *>::doDestroySubTree' :
recursive call has no side effects, deleting

This was fixed in 5.6.0 in QtQTBUG-46649 "MSVC warnings 4718 and 4127 in QMapData".

For every user, every include of Qmap.h, in release mode level 4, will get this warning.

Workaround: (1) : Wrap all "#include <qmap.h>" with
#pragma warning (disable : 4718)
#include <qmap.h>
#pragma warning (default : 4718)

Workaround: (2) : Pragmatize all of-qmap.h OR pragma -doDestroySubTree definitions.
#ifndef QMAP_H
#define QMAP_H
#pragma warning (disable : 4718)
. . .
#pragma warning (default : 4718)
#endif // QMAP_H