Implement QSignalBlocker::dismiss()

...to set m_o to nullptr and prevent an existing QSignalBlocker from
touching the QObject, which it was created for.
Add documentation and implement an autotest.

Change-Id: Ic18e80af5a57df1928f9d36aa0ab7ad79b6525fd
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>

3 files changed, 25 insertions, 0 deletions

diff --git a/src/corelib/kernel/qobject.cpp b/src/corelib/kernel/qobject.cpp
index 7c109238b2..4b767b7b5b 100644
--- a/src/corelib/kernel/qobject.cpp
+++ b/src/corelib/kernel/qobject.cpp
@@ -763,6 +763,14 @@ QMetaCallEvent* QMetaCallEvent::create_impl(QtPrivate::SlotObjUniquePtr slotObj,
 */
 
 /*!
+    \fn void QSignalBlocker::dismiss()
+    \since 6.7
+    Dismisses the QSignalBlocker. It will no longer access the QObject
+    passed to its constructor. unblock(), reblock(), as well as
+    ~QSignalBlocker() will have no effect.
+*/
+
+/*!
     \class QObject
     \inmodule QtCore
     \brief The QObject class is the base class of all Qt objects.
diff --git a/src/corelib/kernel/qobject.h b/src/corelib/kernel/qobject.h
index 7c3d74dcda..a7b2648e45 100644
--- a/src/corelib/kernel/qobject.h
+++ b/src/corelib/kernel/qobject.h
@@ -454,6 +454,7 @@ public:
 
     inline void reblock() noexcept;
     inline void unblock() noexcept;
+    inline void dismiss() noexcept;
 
 private:
     Q_DISABLE_COPY(QSignalBlocker)
@@ -518,6 +519,11 @@ void QSignalBlocker::unblock() noexcept
     m_inhibited = true;
 }
 
+void QSignalBlocker::dismiss() noexcept
+{
+    m_o = nullptr;
+}
+
 namespace QtPrivate {
     inline QObject & deref_for_methodcall(QObject &o) { return  o; }
     inline QObject & deref_for_methodcall(QObject *o) { return *o; }
diff --git a/tests/auto/corelib/kernel/qsignalblocker/tst_qsignalblocker.cpp b/tests/auto/corelib/kernel/qsignalblocker/tst_qsignalblocker.cpp
index 3345707a74..08d40ab8ba 100644
--- a/tests/auto/corelib/kernel/qsignalblocker/tst_qsignalblocker.cpp
+++ b/tests/auto/corelib/kernel/qsignalblocker/tst_qsignalblocker.cpp
@@ -11,6 +11,7 @@ class tst_QSignalBlocker : public QObject
 private slots:
     void signalBlocking();
     void moveAssignment();
+    void dismiss();
 };
 
 void tst_QSignalBlocker::signalBlocking()
@@ -133,5 +134,15 @@ void tst_QSignalBlocker::moveAssignment()
     QVERIFY(!o2.signalsBlocked());
 }
 
+void tst_QSignalBlocker::dismiss()
+{
+    QObject obj;
+    {
+        QSignalBlocker blocker(obj);
+        blocker.dismiss();
+    }
+    QVERIFY(obj.signalsBlocked());
+}
+
 QTEST_MAIN(tst_QSignalBlocker)
 #include "tst_qsignalblocker.moc"