Size conversion warnings using QList<>

On 64-bit MSVC compilations, when using any operation that offsets the iterator of a QList<>, size conversion warnings are emitted.

This may be because QList<>::iterator uses sizeof(qptrdiff) for the difference_type, but uses the int type for the operator+ and operator-.

sizeof(qptrdiff) == 8, but sizeof(int) == 4.

Example code:

#include <QList>
#include <algorithm>

int main(int, char**)
{
    QList<int> l;
    std::stable_sort(l.begin(), l.end());
}

First warning:
C:\Program Files (x86)\Microsoft Visual Studio 12.0\VC\INCLUDE\xutility(690) : warning C4244: 'argument' : conversion from '__int64' to 'int', possible loss of data