QObject: restore flags printing in dumpObjectTree()

This was lost when QtCore, QtGui and QtWidgets were split up. Restored
now via a virtual function on QObjectPrivate.

Chose to return std::string instead of QString or QByteArray because
its SSO is usually sufficient to hold these flag strings.

[ChangeLog][QtCore][QObject] Restored printing of Qt3-style
information from dumpObjectTree().

[ChangeLog][QtWidgets][QWidget] Restored printing of Qt3-style
information from QWidget::dumpObjectTree().

Fixes: QTBUG-101732
Change-Id: I39ff5728ea5f5abbdbf81b5d7e13b8d16b6ee8b7
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>

src/corelib/kernel/qobject.cpp

@@ -4202,27 +4202,18 @@ QList<QByteArray> QObject::dynamicPropertyNames() const
   QObject debugging output routines.
  *****************************************************************************/
 
+std::string QObjectPrivate::flagsForDumping() const
+{
+    return {};
+}
+
 static void dumpRecursive(int level, const QObject *object)
 {
     if (object) {
         const int indent = level * 4;
-        const QString name = object->objectName();
+        qDebug("%*s%s::%ls %s", indent, "", object->metaObject()->className(),
-        QString flags;
+               qUtf16Printable(object->objectName()),
-#if 0
+               QObjectPrivate::get(object)->flagsForDumping().c_str());
-        if (qApp->focusWidget() == object)
-            flags += 'F';
-        if (object->isWidgetType()) {
-            QWidget * w = (QWidget *)object;
-            if (w->isVisible()) {
-                QString t("<%1,%2,%3,%4>");
-                flags += t.arg(w->x()).arg(w->y()).arg(w->width()).arg(w->height());
-            } else {
-                flags += 'I';
-            }
-        }
-#endif
-        qDebug("%*s%s::%ls %ls", indent, "", object->metaObject()->className(),
-               qUtf16Printable(name), qUtf16Printable(flags));
         for (auto child : object->children())
             dumpRecursive(level + 1, child);
     }

src/corelib/kernel/qobject_p.h

@@ -63,6 +63,8 @@
 #include "QtCore/qproperty.h"
 #include "QtCore/private/qproperty_p.h"
 
+#include <string>
+
 QT_BEGIN_NAMESPACE
 
 class QVariant;
@@ -412,6 +414,8 @@ public:
         connections.storeRelaxed(cd);
     }
 
+    virtual std::string flagsForDumping() const;
+
 public:
     mutable ExtraData *extraData; // extra data set by the user
     // This atomic requires acquire/release semantics in a few places,

src/widgets/kernel/qwidget.cpp

@@ -110,6 +110,8 @@
 
 #include "qwindowcontainer_p.h"
 
+#include <sstream>
+
 // widget/widget data creation count
 //#define QWIDGET_EXTRA_DEBUG
 //#define ALIEN_DEBUG
@@ -12961,6 +12963,25 @@ void QWidgetPrivate::setWidgetParentHelper(QObject *widgetAsObject, QObject *new
     widget->setParent(static_cast<QWidget*>(newParent));
 }
 
+std::string QWidgetPrivate::flagsForDumping() const
+{
+    Q_Q(const QWidget);
+    std::string flags = QObjectPrivate::flagsForDumping();
+    if (QApplication::focusWidget() == q)
+        flags += 'F';
+    if (q->isVisible()) {
+        std::stringstream s;
+        s << '<'
+          << q->width() << 'x' << q->height()
+          << std::showpos << q->x() << q->y()
+          << '>';
+        flags += s.str();
+    } else {
+        flags += 'I';
+    }
+    return flags;
+}
+
 void QWidgetPrivate::setNetWmWindowTypes(bool skipIfMissing)
 {
 #if QT_CONFIG(xcb)

src/widgets/kernel/qwidget_p.h

@@ -663,6 +663,8 @@ public:
 
     static void setWidgetParentHelper(QObject *widgetAsObject, QObject *newParent);
 
+    std::string flagsForDumping() const override;
+
     // Variables.
     // Regular pointers (keep them together to avoid gaps on 64 bit architectures).
     std::unique_ptr<QWExtra> extra;

tests/auto/widgets/kernel/qwidget/tst_qwidget.cpp

@@ -335,6 +335,8 @@ private slots:
     void resizeInPaintEvent();
     void opaqueChildren();
 
+    void dumpObjectTree();
+
     void setMaskInResizeEvent();
     void moveInResizeEvent();
 
@@ -9060,6 +9062,44 @@ void tst_QWidget::opaqueChildren()
     QCOMPARE(qt_widget_private(&grandChild)->getOpaqueChildren(), QRegion());
 }
 
+void tst_QWidget::dumpObjectTree()
+{
+    QWidget w;
+    w.setWindowTitle(QLatin1String(QTest::currentTestFunction()));
+    Q_SET_OBJECT_NAME(w);
+    w.move(100, 100);
+    w.resize(500, 500);
+
+    QLineEdit le(&w);
+    Q_SET_OBJECT_NAME(le);
+    le.resize(500, 500);
+
+    {
+        const char * const expected[] = {
+            "QWidget::w I",
+            "    QLineEdit::le I",
+            "        QWidgetLineControl:: ",
+        };
+        for (const char *line : expected)
+            QTest::ignoreMessage(QtDebugMsg, line);
+        w.dumpObjectTree();
+    }
+
+    w.show();
+    QApplication::setActiveWindow(&w);
+    QVERIFY(QTest::qWaitForWindowActive(&w));
+
+    {
+        const char * const expected[] = {
+            "QWidget::w <500x500+100+100>",
+            "    QLineEdit::le F<500x500+0+0>",
+            "        QWidgetLineControl:: ",
+        };
+        for (const char *line : expected)
+            QTest::ignoreMessage(QtDebugMsg, line);
+        w.dumpObjectTree();
+    }
+}
 
 class MaskSetWidget : public QWidget
 {