Don't dereference windowBeingDragged->floatingWindow()

Add a level of indirection instead, and support for the wayland case

src/private/WindowBeingDragged.cpp

@@ -166,6 +166,14 @@ bool WindowBeingDragged::contains(DropArea *dropArea) const
     return m_floatingWindow && m_floatingWindow->dropArea() == dropArea;
 }
 
+QVector<DockWidgetBase *> WindowBeingDragged::dockWidgets() const
+{
+    if (m_floatingWindow)
+        return m_floatingWindow->dockWidgets();
+
+    return {};
+}
+
 Draggable *WindowBeingDragged::draggable() const
 {
     return m_draggable;
@@ -227,6 +235,18 @@ QPixmap WindowBeingDraggedWayland::pixmap() const
     return pixmap;
 }
 
+QVector<DockWidgetBase *> WindowBeingDraggedWayland::dockWidgets() const
+{
+    if (m_floatingWindow)
+        return WindowBeingDragged::dockWidgets();
+    else if (m_frame)
+        return m_frame->dockWidgets();
+    else if (m_dockWidget)
+        return { m_dockWidget };
+
+    return {};
+}
+
 QSize WindowBeingDraggedWayland::size() const
 {
     if (m_floatingWindow)

src/private/WindowBeingDragged_p.h

@@ -64,6 +64,9 @@ public:
     /// @brief Returns a pixmap representing this Window. For purposes of QDrag. Wayland only.
     virtual QPixmap pixmap() const { return {}; }
 
+    /// @brief Returns the list of dock widgets being dragged
+    virtual QVector<DockWidgetBase*> dockWidgets() const;
+
     /// @brief Returns the draggable
     Draggable *draggable() const;
 protected:
@@ -82,16 +85,17 @@ public:
     explicit WindowBeingDraggedWayland(Draggable *draggable);
     ~WindowBeingDraggedWayland() override;
 
+    QSize size() const override;
+    QSize minSize() const override;
+    QSize maxSize() const override;
+    QPixmap pixmap() const override;
+    QVector<DockWidgetBase*> dockWidgets() const override;
+
     // These two are set for Wayland only, where we can't make the floating window immediately (no way to position it)
     // So we're dragging either a frame with multiple dock widgets or a single tab, keep them here.
     // It's important to know what we're dragging, so drop rubber band respect min/max sizes.
     QPointer<Frame> m_frame;
     QPointer<DockWidgetBase> m_dockWidget;
-
-    QSize size() const override;
-    QSize minSize() const override;
-    QSize maxSize() const override;
-    QPixmap pixmap() const override;
 };
 
 }

src/private/indicators/ClassicIndicators.cpp

@@ -105,7 +105,7 @@ void ClassicIndicators::updateIndicatorsVisibility(bool visible)
     m_tabIndicatorVisible = m_innerIndicatorsVisible && windowBeingDragged &&
                             DockRegistry::self()->affinitiesMatch(m_hoveredFrame->affinities(), windowBeingDragged->affinities());
     if (m_tabIndicatorVisible && tabbingAllowedFunc) {
-        const DockWidgetBase::List source = windowBeingDragged->floatingWindow()->dockWidgets();
+        const DockWidgetBase::List source = windowBeingDragged->dockWidgets();
         const DockWidgetBase::List target = m_hoveredFrame->dockWidgets();
         m_tabIndicatorVisible = tabbingAllowedFunc(source, target);
     }