Reject const T*-convertible types in QCommonArrayOps::copyAppend<It>

In many cases (e.g. relocatable and pod), generic version is more
expensive. Let's not expect array data ops to only get QADP iterators
as input. Instead, reject generic version for any const T* -convertible
iterator and force compiler to select copyAppend(const T *b, const T *e)
as a suitable overload

Change-Id: I47a09d35a8ff15322381c2aa28258bfc7deebbad
Reviewed-by: Lars Knoll <lars.knoll@qt.io>
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>

src/corelib/tools/qarraydataops.h

@@ -1267,8 +1267,8 @@ public:
 
     template<typename It>
     void copyAppend(It b, It e, QtPrivate::IfIsForwardIterator<It> = true,
-                    QtPrivate::IfIsNotSame<std::decay_t<It>, iterator> = true,
-                    QtPrivate::IfIsNotSame<std::decay_t<It>, const_iterator> = true)
+                    QtPrivate::IfIsNotConvertible<It, const T *> = true,
+                    QtPrivate::IfIsNotConvertible<It, const T *> = true)
     {
         Q_ASSERT(this->isMutable() || b == e);
         Q_ASSERT(!this->isShared() || b == e);

src/corelib/tools/qcontainertools_impl.h

@@ -147,6 +147,9 @@ using IfAssociativeIteratorHasFirstAndSecond =
 template <typename T, typename U>
 using IfIsNotSame =
     typename std::enable_if<!std::is_same<T, U>::value, bool>::type;
+
+template<typename T, typename U>
+using IfIsNotConvertible = typename std::enable_if<!std::is_convertible<T, U>::value, bool>::type;
 } // namespace QtPrivate
 
 QT_END_NAMESPACE