It is possible for an application to trigger the unexpected result of
NSModalResponseContinue from our call to NSAlert::runModal, by showing
and hiding a modal dialog first, and processing events explicitly. This
at best only flashes the native message box, at worst it triggers an
assert from our processResponse function evaluating that response value
as impossible (via Q_UNREACHABLE).
We should never call processResponse with NSModalResponseContinue,
but instead keep the modal loop running and the dialog visible.
So introduce a wrapper to NSAlert::runModal that keeps calling that
method until we get a result other than NSModalResponseContinue.
Writing an auto test for this failed; a simple test didn't reproduce the
assert; trying to place the opening of the native message box into a
lambda that would be called by the event loop (simulating the button
press from the bug report's reproducer) resulted in the native message
box never closing and the test blocking (and still not triggering the
assert).
Fixes: QTBUG-114546
Pick-to: 6.5 6.6
Change-Id: Iab25eff55c48b103287d1881ac355e6cdd190f7a
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@qt.io>
2c458a8221