QWeakPointer: use an alternative work-round for internalData() users

The previous work-around fails, probably because of
cross-dependencies. E.g. we have this in QtScXml:

In file included from /home/qt/work/install/include/QtCore/qsharedpointer.h:48:0,
                  from ../../src/scxml/qscxmltabledata_p.h:55,
                  from ../../src/scxml/qscxmltabledata.cpp:40:
 /home/qt/work/install/include/QtCore/qsharedpointer_impl.h:687:12: error: ‘QPointer’ does not name a type; did you mean ‘pointer’?
      friend QPointer<X>
             ^~~~~~~~
             pointer
 /home/qt/work/install/include/QtCore/qsharedpointer_impl.h:689:23: error: ‘QSmartPointerConvertFunctor’ in namespace ‘QtPrivate’ does not name a template type
      friend QtPrivate::QSmartPointerConvertFunctor<QWeakPointer>;
                        ^~~~~~~~~~~~~~~~~~~~~~~~~~~

To fix, grand friendship only to a non-template class with a templated
static method that returns internalData(). This fixes most users,
except in qmetatype.h, which does not include qsharedpointer.h. In
order to use the non-template class in there, we need to delay its
name lookup to instantiation time. We do this by artificially making
it a dependent name, by using a class template that inherits from
our befrieded class.

Change-Id: I12b427f1fe9503df819ea5436d780972d6402e68
Reviewed-by: Ville Voutilainen <ville.voutilainen@qt.io>
 
 
 
 
 
 
 
 
 
 
 
 
 
 

2 files changed, 8 insertions, 2 deletions

diff --git a/src/corelib/kernel/qmetatype.h b/src/corelib/kernel/qmetatype.h
index 154ccf62bb..fef25a32c4 100644
--- a/src/corelib/kernel/qmetatype.h
+++ b/src/corelib/kernel/qmetatype.h
@@ -1715,12 +1715,17 @@ namespace QtPrivate {
         }
     };
 
+    // hack to delay name lookup to instantiation time by making
+    // EnableInternalData a dependent name:
+    template <typename T>
+    struct EnableInternalDataWrap;
+
     template<typename T>
     struct QSmartPointerConvertFunctor<QWeakPointer<T> >
     {
         QObject* operator()(const QWeakPointer<T> &p) const
         {
-            return p.internalData();
+            return QtPrivate::EnableInternalDataWrap<T>::internalData(p);
         }
     };
 }
diff --git a/src/corelib/kernel/qpointer.h b/src/corelib/kernel/qpointer.h
index 80faef2990..7052bcf0d4 100644
--- a/src/corelib/kernel/qpointer.h
+++ b/src/corelib/kernel/qpointer.h
@@ -143,7 +143,8 @@ template<typename T>
 QPointer<T>
 qPointerFromVariant(const QVariant &variant)
 {
-    return QPointer<T>(qobject_cast<T*>(QtSharedPointer::weakPointerFromVariant_internal(variant).internalData()));
+    const auto wp = QtSharedPointer::weakPointerFromVariant_internal(variant);
+    return QPointer<T>{qobject_cast<T*>(QtPrivate::EnableInternalData::internalData(wp))};
 }
 
 template <class T>