QtWidgets: Fix errors about fields from anonymous namespaces (-Werror=subobject-linkage)

Move types to QtPrivate, fixing errors like:

error: QCalendarWidgetPrivate’ has a field
QCalendarWidgetPrivate::m_model whose type uses the anonymous namespace [-Werror=subobject-linkage]

The error appears in CMake Unity (Jumbo) builds apparently
due to multiple anonymous namespaces per file.

Task-number: QTBUG-109394
Pick-to: 6.5
Change-Id: Id678af4db5633b1b2267425c7751f1312935d5d5
Reviewed-by: Axel Spoerl <axel.spoerl@qt.io>
Reviewed-by: Jan Arve Sæther <jan-arve.saether@qt.io>

1 files changed, 5 insertions, 2 deletions

diff --git a/src/printsupport/widgets/qprintpreviewwidget.cpp b/src/printsupport/widgets/qprintpreviewwidget.cpp
index fa33cf66b8..1b75e526d1 100644
--- a/src/printsupport/widgets/qprintpreviewwidget.cpp
+++ b/src/printsupport/widgets/qprintpreviewwidget.cpp
@@ -14,7 +14,7 @@
 
 QT_BEGIN_NAMESPACE
 
-namespace {
+namespace QtPrivate {
 class PageItem : public QGraphicsItem
 {
 public:
@@ -136,7 +136,10 @@ protected:
     }
 };
 
-} // anonymous namespace
+} // namespace QtPrivate
+
+using GraphicsView = QtPrivate::GraphicsView;
+using PageItem = QtPrivate::PageItem;
 
 class QPrintPreviewWidgetPrivate : public QWidgetPrivate
 {