QModelIndex should support qint64 for its row and colum properties

I'm well aware of how implausible the concept of a ListView with more than 2,147,483,647 items is. But, for theoretical correctness (if anything), should a QAbstractItemModel and its QModelIndex's row API support qint64.

We are developing a large QML application for the German CNC industry. In that application we have a component called the "Editor" for which I am one of the designated architects.

This editor will display so called Klartext programming statements. Or it will display so called DIN/ISO programming statements. Such programming statements direct a CNC machine to perform a certain action. For example: move the X, Y and Z axis a certain amount of millimeter in their respective directions.

A typical program will contain millions of such statements.

We want to visualize said statements in QML. Using a QML component. Realizing the existing ListView in QML cannot cope with such amounts we decided early on to develop a custom View component. Everybody claiming that extravagant amounts are not what QML is designed to do, is probably right. But their defense for QML ain't at all the point of this bug report (remember, we made our own QML component, and we did so successfully).

We however prefer to stick to Qt's standard APIs as much as possible. We think that QAbstractItemModel is a good "model" API for such a custom QML View implementation.

However, unfortunately is QAbstractItemModel's QModelIndex's row() API a int based one.

We think it should support qint64.