Wrap calls to Sequence::push_back

In C++11 push_back is overloaded to support rvalue-references,

   void std::vector<T>::push_back(const T &);
   void std::vector<T>::push_back(T &&);

so attempting to get the address for push_back is ambiguous.

Instead of hardcoding the function signature, the better and more
general solution is to allow the compiler to do the required overload
resolution itself, also allowing for implicit conversions to take place.

Task-number: QTBUG-18996
Done-with: Liang Qi
Reviewed-by: Olivier Goffart
(cherry picked from commit ca34cc75294e0d2a8bc491a2c679fe8a69cd0408)

Change-Id: Id271118e489f888905e491dd4cfc3d2db7697552
Reviewed-on: http://codereview.qt-project.org/4642
Reviewed-by: Liang Qi <liang.qi@nokia.com>
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>

src/corelib/concurrent/qtconcurrentfilter.h

@@ -102,10 +102,9 @@ namespace QtConcurrent {
 
 namespace QtConcurrent {
 
-template <typename Sequence, typename KeepFunctor, typename T, typename C, typename U>
-ThreadEngineStarter<void> filterInternal(Sequence &sequence, KeepFunctor keep, T (C::*reduce)(U))
+template <typename Sequence, typename KeepFunctor, typename ReduceFunctor>
+ThreadEngineStarter<void> filterInternal(Sequence &sequence, KeepFunctor keep, ReduceFunctor reduce)
 {
-    typedef MemberFunctionWrapper1<T, C, U> ReduceFunctor;
     typedef typename Sequence::const_iterator Iterator;
     typedef FilterKernel<Sequence, KeepFunctor, ReduceFunctor> KernelType;
     return startThreadEngine(new KernelType(sequence, keep, reduce));
@@ -115,7 +114,7 @@ ThreadEngineStarter<void> filterInternal(Sequence &sequence, KeepFunctor keep, T
 template <typename Sequence, typename KeepFunctor>
 QFuture<void> filter(Sequence &sequence, KeepFunctor keep)
 {
-    return filterInternal(sequence, QtPrivate::createFunctionWrapper(keep), &Sequence::push_back);
+    return filterInternal(sequence, QtPrivate::createFunctionWrapper(keep), QtPrivate::PushBackWrapper());
 }
 
 // filteredReduced() on sequences
@@ -184,7 +183,7 @@ QFuture<typename qValueType<Iterator>::value_type> filtered(Iterator begin, Iter
 template <typename Sequence, typename KeepFunctor>
 void blockingFilter(Sequence &sequence, KeepFunctor keep)
 {
-    filterInternal(sequence, QtPrivate::createFunctionWrapper(keep), &Sequence::push_back).startBlocking();
+    filterInternal(sequence, QtPrivate::createFunctionWrapper(keep), QtPrivate::PushBackWrapper()).startBlocking();
 }
 
 // blocking filteredReduced() on sequences
@@ -246,18 +245,17 @@ typename QtPrivate::ReduceResultType<ReduceFunctor>::ResultType blockingFiltered
 template <typename Sequence, typename KeepFunctor>
 Sequence blockingFiltered(const Sequence &sequence, KeepFunctor keep)
 {
-    return blockingFilteredReduced(sequence, QtPrivate::createFunctionWrapper(keep), &Sequence::push_back, OrderedReduce);
+    return startFilteredReduced<Sequence>(sequence, QtPrivate::createFunctionWrapper(keep), QtPrivate::PushBackWrapper(), OrderedReduce).startBlocking();
 }
 
 // blocking filtered() on iterators
 template <typename OutputSequence, typename Iterator, typename KeepFunctor>
 OutputSequence blockingFiltered(Iterator begin, Iterator end, KeepFunctor keep)
 {
-    return blockingFilteredReduced(begin,
-                                   end,
-                                   QtPrivate::createFunctionWrapper(keep),
-                                   &OutputSequence::push_back,
-                                   OrderedReduce);
+    return startFilteredReduced<OutputSequence>(begin, end,
+        QtPrivate::createFunctionWrapper(keep),
+        QtPrivate::PushBackWrapper(),
+        OrderedReduce).startBlocking();
 }
 
 } // namespace QtConcurrent

src/corelib/concurrent/qtconcurrentfunctionwrappers.h

@@ -195,6 +195,25 @@ QtConcurrent::ConstMemberFunctionWrapper<T, C> createFunctionWrapper(T (C::*func
     return QtConcurrent::ConstMemberFunctionWrapper<T, C>(func);
 }
 
+struct PushBackWrapper
+{
+    typedef void result_type;
+
+    template <class C, class U>
+    inline void operator()(C &c, const U &u) const
+    {
+        return c.push_back(u);
+    }
+
+#ifdef Q_COMPILER_RVALUE_REFS
+    template <class C, class U>
+    inline void operator()(C &c, U &&u) const
+    {
+        return c.push_back(u);
+    }
+#endif
+};
+
 template <typename Functor, bool foo = HasResultType<Functor>::Value>
 struct LazyResultType { typedef typename Functor::result_type Type; };
 template <typename Functor>

src/corelib/concurrent/qtconcurrentmap.h

@@ -271,7 +271,7 @@ OutputSequence blockingMapped(const InputSequence &sequence, MapFunctor map)
     return blockingMappedReduced<OutputSequence>
         (sequence,
          QtPrivate::createFunctionWrapper(map),
-         &OutputSequence::push_back,
+         QtPrivate::PushBackWrapper(),
          QtConcurrent::OrderedReduce);
 }
 
@@ -282,7 +282,7 @@ typename QtPrivate::MapResultType<InputSequence, MapFunctor>::ResultType blockin
     return blockingMappedReduced<OutputSequence>
         (sequence,
          QtPrivate::createFunctionWrapper(map),
-         &OutputSequence::push_back,
+         QtPrivate::PushBackWrapper(),
          QtConcurrent::OrderedReduce);
 }
 
@@ -293,7 +293,7 @@ Sequence blockingMapped(Iterator begin, Iterator end, MapFunctor map)
     return blockingMappedReduced<Sequence>
         (begin, end,
          QtPrivate::createFunctionWrapper(map),
-         &Sequence::push_back,
+         QtPrivate::PushBackWrapper(),
          QtConcurrent::OrderedReduce);
 }
 
@@ -304,7 +304,7 @@ typename QtPrivate::MapResultType<Iterator, MapFunctor>::ResultType blockingMapp
     return blockingMappedReduced<OutputSequence>
         (begin, end,
          QtPrivate::createFunctionWrapper(map),
-         &OutputSequence::push_back,
+         QtPrivate::PushBackWrapper(),
          QtConcurrent::OrderedReduce);
 }
 

tests/auto/corelib/concurrent/qtconcurrentmap/tst_qtconcurrentmap.cpp

@@ -2320,11 +2320,6 @@ void tst_QtConcurrentMap::stlContainers()
 {
 #ifdef QT_NO_STL
     QSKIP("Qt compiled without STL support", SkipAll);
-#elif defined(Q_COMPILER_RVALUE_REFS)
-    //mapped uses &Container::push_back,  but in c++0x, std::vector has two overload of it
-    // meaning it is not possible to take the address of that function anymore.
-    QSKIP("mapped do not work with c++0x stl vector", SkipAll);
-#else
     std::vector<int> vector;
     vector.push_back(1);
     vector.push_back(2);