Add a unit test to QSharedPointer being deleted by a C++11 lambda

This already worked, but let's have a test so we can be sure it doesn't
regress.

Change-Id: I358b436d216e3ec4310f05ccf4f70f9e7aad3281
Reviewed-by: Stephen Kelly <stephen.kelly@kdab.com>
Reviewed-by: Lars Knoll <lars.knoll@nokia.com>

tests/auto/corelib/tools/qsharedpointer/tst_qsharedpointer.cpp

@@ -89,6 +89,7 @@ private slots:
 #endif
     void constCorrectness();
     void customDeleter();
+    void lambdaCustomDeleter();
     void creating();
     void creatingQObject();
     void mixTrackingPointerCode();
@@ -1336,6 +1337,37 @@ void tst_QSharedPointer::customDeleter()
     safetyCheck();
 }
 
+void tst_QSharedPointer::lambdaCustomDeleter()
+{
+#ifndef Q_COMPILER_LAMBDA
+    QSKIP("This compiler is not in C++11 mode or does not support lambdas");
+#else
+    {
+        // stateless, one-argument
+        QSharedPointer<Data> ptr(new Data, [](Data *d) { delete d; });
+        QSharedPointer<Data> ptr2(new Data, [](Data *d) { d->doDelete(); });
+    }
+    safetyCheck();
+
+    customDeleterFnCallCount = 0;
+    {
+        // stateless, one-argument, modifies globals
+        QSharedPointer<Data> ptr(new Data, [](Data *d) { ++customDeleterFnCallCount; delete d; });
+    }
+    safetyCheck();
+    QCOMPARE(customDeleterFnCallCount, 1);
+
+    {
+        // stateful by ref, one-argument
+        int i = 0;
+        QSharedPointer<Data> ptr(new Data, [&i](Data *d) { i = 42; delete d; });
+        ptr.clear();
+        QCOMPARE(i, 42);
+    }
+    safetyCheck();
+#endif
+}
+
 void customQObjectDeleterFn(QObject *obj)
 {
     ++customDeleterFnCallCount;