QGraphicsView: replace some Q_FOREACH loops over rvalues with C++11 range-for

This needs to be handled a bit carefully, because Qt containers
will detach upon being iterated over using range-for.

In the cases of this patch, that trivially cannot happen, because
all containers are marked as const when being assigned the rvalues
previously found on the rhs of the Q_FOREACH. The new code thus
does exactly what the old code did: take a const copy, then iterate
over it.

Separate patches will deal with other situations.

Range-for loops are much more efficient than foreach loops.

This patch shaves almost 4K of text size off an optimized Linux
AMD64 GCC 4.9 build.

Change-Id: Ida868b77d078cbfa0516d17e98e6f0a86fcdb7a3
Reviewed-by: Olivier Goffart (Woboq GmbH) <ogoffart@woboq.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/src/widgets/graphicsview/qgraphicswidget.cpp b/src/widgets/graphicsview/qgraphicswidget.cpp
index ef086aeab0..db1cdd42ab 100644
--- a/src/widgets/graphicsview/qgraphicswidget.cpp
+++ b/src/widgets/graphicsview/qgraphicswidget.cpp
@@ -251,7 +251,8 @@ QGraphicsWidget::~QGraphicsWidget()
     //we check if we have a layout previously
     if (d->layout) {
         QGraphicsLayout *temp = d->layout;
-        foreach (QGraphicsItem * item, childItems()) {
+        const auto items = childItems();
+        for (QGraphicsItem *item : items) {
             // In case of a custom layout which doesn't remove and delete items, we ensure that
             // the parent layout item does not point to the deleted layout. This code is here to
             // avoid regression from 4.4 to 4.5, because according to 4.5 docs it is not really needed.