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/qgraphicsproxywidget.cpp b/src/widgets/graphicsview/qgraphicsproxywidget.cpp
index 3ea04efc6b..ea9fc0a0d5 100644
--- a/src/widgets/graphicsview/qgraphicsproxywidget.cpp
+++ b/src/widgets/graphicsview/qgraphicsproxywidget.cpp
@@ -595,7 +595,8 @@ void QGraphicsProxyWidgetPrivate::setWidget_helper(QWidget *newWidget, bool auto
         resolvePalette(inheritedPaletteResolveMask);
         widget->update();
 
-        foreach (QGraphicsItem *child, q->childItems()) {
+        const auto childItems = q->childItems();
+        for (QGraphicsItem *child : childItems) {
             if (child->d_ptr->isProxyWidget()) {
                 QGraphicsProxyWidget *childProxy = static_cast<QGraphicsProxyWidget *>(child);
                 QWidget * parent = childProxy->widget();