QFramePrivate & subclasses: declare dtor out-of-line

De-duplicates vtables and enables RTTI on this class
hierarchy.

Export QFramePrivate, as QAbstractScrollAreaPrivate
(a subclass) is exported, too.

Change-Id: I541886373435dc49c4267190a7191e2436f4c95e
Reported-by: Volker Krause <volker.krause@kdab.com>
Task-number: QTBUG-45582
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@theqtcompany.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

src/widgets/widgets/qabstractscrollarea.cpp

@@ -168,6 +168,10 @@ QAbstractScrollAreaPrivate::QAbstractScrollAreaPrivate()
 {
 }
 
+QAbstractScrollAreaPrivate::~QAbstractScrollAreaPrivate()
+{
+}
+
 QAbstractScrollAreaScrollBarContainer::QAbstractScrollAreaScrollBarContainer(Qt::Orientation orientation, QWidget *parent)
     :QWidget(parent), scrollBar(new QScrollBar(orientation, this)),
      layout(new QBoxLayout(orientation == Qt::Horizontal ? QBoxLayout::LeftToRight : QBoxLayout::TopToBottom)),

src/widgets/widgets/qabstractscrollarea_p.h

@@ -54,12 +54,15 @@ QT_BEGIN_NAMESPACE
 
 class QScrollBar;
 class QAbstractScrollAreaScrollBarContainer;
+
+// ### Qt 6: is the export still needed? If not, unexport QFramePrivate, too.
 class Q_WIDGETS_EXPORT QAbstractScrollAreaPrivate: public QFramePrivate
 {
     Q_DECLARE_PUBLIC(QAbstractScrollArea)
 
 public:
     QAbstractScrollAreaPrivate();
+    ~QAbstractScrollAreaPrivate();
 
     void replaceScrollBar(QScrollBar *scrollBar, Qt::Orientation orientation);
 

src/widgets/widgets/qframe.cpp

@@ -55,6 +55,10 @@ QFramePrivate::QFramePrivate()
 {
 }
 
+QFramePrivate::~QFramePrivate()
+{
+}
+
 inline void QFramePrivate::init()
 {
     setLayoutItemMargins(QStyle::SE_FrameLayoutItem);

src/widgets/widgets/qframe_p.h

@@ -50,11 +50,13 @@
 
 QT_BEGIN_NAMESPACE
 
-class QFramePrivate : public QWidgetPrivate
+// ### unexport this class when and if QAbstractScrollAreaPrivate is unexported
+class Q_WIDGETS_EXPORT QFramePrivate : public QWidgetPrivate
 {
     Q_DECLARE_PUBLIC(QFrame)
 public:
     QFramePrivate();
+    ~QFramePrivate();
 
     void        updateFrameWidth();
     void        updateStyledFrameWidths();

src/widgets/widgets/qlabel.cpp

@@ -53,6 +53,10 @@
 
 QT_BEGIN_NAMESPACE
 
+QLabelPrivate::~QLabelPrivate()
+{
+}
+
 /*!
     \class QLabel
     \brief The QLabel widget provides a text or image display.

src/widgets/widgets/qlabel_p.h

@@ -65,6 +65,7 @@ class QLabelPrivate : public QFramePrivate
     Q_DECLARE_PUBLIC(QLabel)
 public:
     QLabelPrivate() {}
+    ~QLabelPrivate();
 
     void init();
     void clearContents();

src/widgets/widgets/qsplitter.cpp

@@ -58,6 +58,10 @@ QT_BEGIN_NAMESPACE
 
 //#define QSPLITTER_DEBUG
 
+QSplitterPrivate::~QSplitterPrivate()
+{
+}
+
 /*!
     \class QSplitterHandle
     \brief The QSplitterHandle class provides handle functionality for the splitter.

src/widgets/widgets/qsplitter_p.h

@@ -76,6 +76,7 @@ class QSplitterPrivate : public QFramePrivate
 public:
     QSplitterPrivate() : rubberBand(0), opaque(true), firstShow(true),
                          childrenCollapsible(true), compatMode(false), handleWidth(-1), blockChildAdd(false), opaqueResizeSet(false) {}
+    ~QSplitterPrivate();
 
     QPointer<QRubberBand> rubberBand;
     mutable QList<QSplitterLayoutStruct *> list;