QAbstractItemModel: fix persistent index corruption when moving columns

QHeaderView creates persistent indexes in
_q_sectionsAboutToBeChanged(), called by the slot connected to
rowsAboutToBeMoved/columnsAboutToBeMoved.

In the case of rows, QAbstractItemModel emits the signal *before*
preparing to update persistent indexes in itemsAboutToBeMoved(),
so it can see the ones newly created by QHeaderView, all is well.

In the case of columns, the emit was done *after* calling
itemsAboutToBeMoved(), so the additional persistent indexes created by
QHeaderView were ignored, and in endMoveRows() we could end up with:
ASSERT failure in QPersistentModelIndex::~QPersistentModelIndex: "persistent model indexes corrupted"

This bug has been there since the very beginning of beginMoveColumns(),
but was undetected because moving columns in a model is pretty rare
(in my case there's a QTransposeProxyModel that turns columns into
rows in the underlying model, and a proxy that handles dropMimeData...)

Pick-to: 6.3 6.2 5.15
Change-Id: I74bad137594019a04c2a19c2abb351ff3065c25a
Reviewed-by: Andreas Buhr <andreas.buhr@qt.io>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Giuseppe D'Angelo <giuseppe.dangelo@kdab.com>

0 files changed, 0 insertions, 0 deletions