From e22a230a039a392e71322cb63610d07885a45168 Mon Sep 17 00:00:00 2001
From: Thiago Macieira <thiago.macieira@intel.com>
Date: Thu, 14 Apr 2016 16:23:22 -0700
Subject: Make QSharedPointer without custom deleters call the correct
 destructor

Where "correct" is defined by what std::shared_ptr does as well as what
happens when an intermediate QSharedPointer of the exact type of the
constructor behaves

That is,
   QSharedPointer<X> ptr(new Y);

Behaves like
   QSharedPointer<X> ptr;
   { QSharedPointer<Y> tmp(new Y); ptr = tmp; }

Change-Id: Id75834dab9ed466e94c7ffff14455d445f72592b
Reviewed-by: Olivier Goffart (Woboq GmbH) <ogoffart@woboq.com>
Reviewed-by: Marc Mutz <marc.mutz@kdab.com>
---
 src/corelib/tools/qsharedpointer.cpp               |  8 +++
 src/corelib/tools/qsharedpointer_impl.h            |  6 +-
 .../tools/qsharedpointer/tst_qsharedpointer.cpp    | 78 ++++++++++++++++++++++
 3 files changed, 89 insertions(+), 3 deletions(-)

diff --git a/src/corelib/tools/qsharedpointer.cpp b/src/corelib/tools/qsharedpointer.cpp
index f420c6237b..c369ff8697 100644
--- a/src/corelib/tools/qsharedpointer.cpp
+++ b/src/corelib/tools/qsharedpointer.cpp
@@ -447,6 +447,11 @@
     Creates a QSharedPointer that points to \a ptr. The pointer \a ptr
     becomes managed by this QSharedPointer and must not be passed to
     another QSharedPointer object or deleted outside this object.
+
+    Since Qt 5.8, when the last reference to this QSharedPointer gets
+    destroyed, \a ptr will be deleted by calling \c X's destructor (even if \c
+    X is not the same as QSharedPointer's template parameter \c T). Previously,
+    the destructor for \c T was called.
 */
 
 /*!
@@ -477,6 +482,9 @@
     }
     \endcode
 
+    Note that the custom deleter function will be called with a pointer to type
+    \c X, even if the QSharedPointer template parameter \c T is not the same.
+
     It is also possible to specify a member function directly, as in:
     \code
         QSharedPointer<MyObject> obj =
diff --git a/src/corelib/tools/qsharedpointer_impl.h b/src/corelib/tools/qsharedpointer_impl.h
index b9b29e926d..bbac2d0327 100644
--- a/src/corelib/tools/qsharedpointer_impl.h
+++ b/src/corelib/tools/qsharedpointer_impl.h
@@ -518,15 +518,15 @@ private:
 
     inline void enableSharedFromThis(...) {}
 
-    template <typename Deleter>
-    inline void internalConstruct(T *ptr, Deleter deleter)
+    template <typename X, typename Deleter>
+    inline void internalConstruct(X *ptr, Deleter deleter)
     {
         if (!ptr) {
             d = Q_NULLPTR;
             return;
         }
 
-        typedef QtSharedPointer::ExternalRefCountWithCustomDeleter<T, Deleter> Private;
+        typedef QtSharedPointer::ExternalRefCountWithCustomDeleter<X, Deleter> Private;
 # ifdef QT_SHAREDPOINTER_TRACK_POINTERS
         typename Private::DestroyerFn actualDeleter = &Private::safetyCheckDeleter;
 # else
diff --git a/tests/auto/corelib/tools/qsharedpointer/tst_qsharedpointer.cpp b/tests/auto/corelib/tools/qsharedpointer/tst_qsharedpointer.cpp
index f48e81ed91..7998f7b7fd 100644
--- a/tests/auto/corelib/tools/qsharedpointer/tst_qsharedpointer.cpp
+++ b/tests/auto/corelib/tools/qsharedpointer/tst_qsharedpointer.cpp
@@ -63,6 +63,7 @@ private slots:
     void useOfForwardDeclared();
     void memoryManagement();
     void dropLastReferenceOfForwardDeclared();
+    void nonVirtualDestructors();
     void lock();
     void downCast();
     void functionCallDownCast();
@@ -603,6 +604,56 @@ void tst_QSharedPointer::dropLastReferenceOfForwardDeclared()
     QCOMPARE(forwardDeclaredDestructorRunCount, 1);
 }
 
+// NVD for "non-virtual destructor"
+struct NVDData
+{
+    static int destructorCounter;
+    ~NVDData() { ++destructorCounter; }
+
+    int dummy;
+};
+int NVDData::destructorCounter;
+
+struct NVDDerivedData : NVDData
+{
+    static int destructorCounter;
+    ~NVDDerivedData() { ++destructorCounter; }
+};
+int NVDDerivedData::destructorCounter;
+
+void tst_QSharedPointer::nonVirtualDestructors()
+{
+    NVDData::destructorCounter = NVDDerivedData::destructorCounter = 0;
+    {
+        QSharedPointer<NVDData> ptr(new NVDData);
+    }
+    QCOMPARE(NVDData::destructorCounter, 1);
+    QCOMPARE(NVDDerivedData::destructorCounter, 0);
+
+    NVDData::destructorCounter = NVDDerivedData::destructorCounter = 0;
+    {
+        QSharedPointer<NVDDerivedData> ptr(new NVDDerivedData);
+    }
+    QCOMPARE(NVDData::destructorCounter, 1);
+    QCOMPARE(NVDDerivedData::destructorCounter, 1);
+
+    NVDData::destructorCounter = NVDDerivedData::destructorCounter = 0;
+    {
+        QSharedPointer<NVDData> bptr;
+        QSharedPointer<NVDDerivedData> ptr(new NVDDerivedData);
+        bptr = ptr;
+    }
+    QCOMPARE(NVDData::destructorCounter, 1);
+    QCOMPARE(NVDDerivedData::destructorCounter, 1);
+
+    NVDData::destructorCounter = NVDDerivedData::destructorCounter = 0;
+    {
+        QSharedPointer<NVDData> ptr(new NVDDerivedData);
+    }
+    QCOMPARE(NVDData::destructorCounter, 1);
+    QCOMPARE(NVDDerivedData::destructorCounter, 1);
+}
+
 void tst_QSharedPointer::lock()
 {
     QSharedPointer<int> sp = QSharedPointer<int>::create();
@@ -1529,6 +1580,33 @@ void tst_QSharedPointer::customDeleter()
     QCOMPARE(refcount, 2);
     safetyCheck();
 
+    CustomDeleter<NVDData> nvdeleter;
+    nvdeleter.callCount = 0;
+    {
+        QSharedPointer<NVDData> ptr(new NVDData, nvdeleter);
+    }
+    QCOMPARE(nvdeleter.callCount, 1);
+    safetyCheck();
+
+    CustomDeleter<NVDDerivedData> nvderiveddeleter;
+    nvdeleter.callCount = 0;
+    nvderiveddeleter.callCount = 0;
+    {
+        QSharedPointer<NVDDerivedData> ptr(new NVDDerivedData, nvderiveddeleter);
+    }
+    QCOMPARE(nvdeleter.callCount, 0);
+    QCOMPARE(nvderiveddeleter.callCount, 1);
+    safetyCheck();
+
+    nvdeleter.callCount = 0;
+    nvderiveddeleter.callCount = 0;
+    {
+        QSharedPointer<NVDData> ptr(new NVDDerivedData, nvderiveddeleter);
+    }
+    QCOMPARE(nvdeleter.callCount, 0);
+    QCOMPARE(nvderiveddeleter.callCount, 1);
+    safetyCheck();
+
     // a custom deleter with a different pointer parameter
     {
         QSharedPointer<char> ptr(static_cast<char *>(malloc(1)), free);
-- 
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