Support C++17 fallthrough attribute

Replaces our mix of comments for annotating intended absence of break
in switches with the C++17 attribute [[fallthrough]], or its earlier
a clang extension counterpart.

Change-Id: I4b2d0b9b5e4425819c7f1bf01608093c536b6d14
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

2 files changed, 4 insertions, 4 deletions

diff --git a/src/widgets/itemviews/qheaderview.cpp b/src/widgets/itemviews/qheaderview.cpp
index 7b393463a6..6f1e301d4f 100644
--- a/src/widgets/itemviews/qheaderview.cpp
+++ b/src/widgets/itemviews/qheaderview.cpp
@@ -2563,7 +2563,7 @@ void QHeaderView::mouseReleaseEvent(QMouseEvent *e)
             int section = logicalIndexAt(pos);
             updateSection(section);
         }
-        // fall through
+        Q_FALLTHROUGH();
     case QHeaderViewPrivate::NoState:
         if (d->clickableSections) {
             int section = logicalIndexAt(pos);
@@ -2669,7 +2669,7 @@ bool QHeaderView::viewportEvent(QEvent *e)
     case QEvent::FontChange:
     case QEvent::StyleChange:
         d->invalidateCachedSizeHint();
-        // Fall through
+        Q_FALLTHROUGH();
     case QEvent::Hide:
     case QEvent::Show: {
         QAbstractScrollArea *parent = qobject_cast<QAbstractScrollArea *>(parentWidget());
diff --git a/src/widgets/itemviews/qtreewidget.cpp b/src/widgets/itemviews/qtreewidget.cpp
index 74ca7d2827..5e0f13277c 100644
--- a/src/widgets/itemviews/qtreewidget.cpp
+++ b/src/widgets/itemviews/qtreewidget.cpp
@@ -1737,7 +1737,7 @@ void QTreeWidgetItem::setData(int column, int role, const QVariant &value)
                 }
             }
         }
-        // Don't break, but fall through
+        Q_FALLTHROUGH();
     default:
         if (column < values.count()) {
             bool found = false;
@@ -1787,7 +1787,7 @@ QVariant QTreeWidgetItem::data(int column, int role) const
         // special case for check state in tristate
         if (children.count() && (itemFlags & Qt::ItemIsAutoTristate))
             return childrenCheckState(column);
-        // fallthrough intended
+        Q_FALLTHROUGH();
    default:
         if (column >= 0 && column < values.size()) {
             const QVector<QWidgetItemData> &column_values = values.at(column);