QMdiArea: port Q_FOREACH to ranged-for, d->pendingPlacements

Pick-to: 6.6 6.5
Task-number: QTBUG-115803
Change-Id: Ibf2f049aacad925fea318c0ec490749e68e05b1d
Reviewed-by: Richard Moe Gustavsen <richard.gustavsen@qt.io>

src/widgets/widgets/qmdiarea.cpp

@@ -2345,7 +2345,12 @@ void QMdiArea::showEvent(QShowEvent *showEvent)
     }
 
     if (!d->pendingPlacements.isEmpty()) {
-        foreach (QMdiSubWindow *window, d->pendingPlacements) {
+        // Nothing obvious in the loop body changes the container (in this code path)
+        // during iteration, this is calling into a non-const method that does change
+        // the container when called from other places. So take a copy anyway for good
+        // measure.
+        const auto copy = d->pendingPlacements;
+        for (QMdiSubWindow *window : copy) {
             if (!window)
                 continue;
             if (!window->testAttribute(Qt::WA_Resized)) {