4 files changed, 30 insertions, 0 deletions
diff --git a/src/corelib/tools/qsharedpointer.cpp b/src/corelib/tools/qsharedpointer.cpp
index a610fc46e5..19c88fcf1c 100644
--- a/src/corelib/tools/qsharedpointer.cpp
+++ b/src/corelib/tools/qsharedpointer.cpp
@@ -894,6 +894,15 @@
 */
 
 /*!
+    \fn QSharedPointer<T> QWeakPointer::lock() const
+    \since 5.4
+
+    Same as toStrongRef().
+
+    This function is provided for API compatibility with std::weak_ptr.
+*/
+
+/*!
     \fn void QWeakPointer::clear()
 
     Clears this QWeakPointer object, dropping the reference that it
diff --git a/src/corelib/tools/qsharedpointer.h b/src/corelib/tools/qsharedpointer.h
index 34b4bfbb12..ea9b4fbf27 100644
--- a/src/corelib/tools/qsharedpointer.h
+++ b/src/corelib/tools/qsharedpointer.h
@@ -126,6 +126,7 @@ public:
     void clear();
 
     QSharedPointer<T> toStrongRef() const;
+    QSharedPointer<T> lock() const;
 };
 
 template<class T, class X> bool operator==(const QSharedPointer<T> &ptr1, const QSharedPointer<X> &ptr2);
diff --git a/src/corelib/tools/qsharedpointer_impl.h b/src/corelib/tools/qsharedpointer_impl.h
index c077b84492..e59efce7ae 100644
--- a/src/corelib/tools/qsharedpointer_impl.h
+++ b/src/corelib/tools/qsharedpointer_impl.h
@@ -639,6 +639,8 @@ public:
     inline void clear() { *this = QWeakPointer(); }
 
     inline QSharedPointer<T> toStrongRef() const { return QSharedPointer<T>(*this); }
+    // std::weak_ptr compatibility:
+    inline QSharedPointer<T> lock() const { return toStrongRef(); }
 
 #if defined(QWEAKPOINTER_ENABLE_ARROW)
     inline T *operator->() const { return data(); }
diff --git a/tests/auto/corelib/tools/qsharedpointer/tst_qsharedpointer.cpp b/tests/auto/corelib/tools/qsharedpointer/tst_qsharedpointer.cpp
index 8c76e6b440..1d466a4734 100644
--- a/tests/auto/corelib/tools/qsharedpointer/tst_qsharedpointer.cpp
+++ b/tests/auto/corelib/tools/qsharedpointer/tst_qsharedpointer.cpp
@@ -74,6 +74,7 @@ private slots:
     void useOfForwardDeclared();
     void memoryManagement();
     void dropLastReferenceOfForwardDeclared();
+    void lock();
     void downCast();
     void functionCallDownCast();
     void upCast();
@@ -494,6 +495,22 @@ void tst_QSharedPointer::dropLastReferenceOfForwardDeclared()
     QCOMPARE(forwardDeclaredDestructorRunCount, 1);
 }
 
+void tst_QSharedPointer::lock()
+{
+    QSharedPointer<int> sp = QSharedPointer<int>::create();
+    QVERIFY(sp);
+    QWeakPointer<int> wp = sp;
+    QVERIFY(sp == wp);
+    QVERIFY(sp == wp.lock());
+    QVERIFY(sp == wp.toStrongRef());
+
+    sp.reset();
+    QVERIFY(!wp);
+    QVERIFY(sp != wp); // this is why op(shared_ptr, weak_ptr) is a bad idea (apart from MT races)...
+    QVERIFY(sp == wp.lock());
+    QVERIFY(sp == wp.toStrongRef());
+}
+
 class DerivedData: public Data
 {
 public:
@@ -866,6 +883,7 @@ void tst_QSharedPointer::objectCast()
         ptr.clear();
         QVERIFY(ptr.isNull());
         QVERIFY(weakptr.toStrongRef().isNull());
+        QVERIFY(weakptr.lock().isNull());
 
         // verify that the object casts fail without crash
         QSharedPointer<OtherObject> otherptr = qSharedPointerObjectCast<OtherObject>(weakptr);