QVariant of nullptr should always be null

Implements isNull for QVariants of a nullptr so they always return
true to isNull(), instead of depending on how they were constructed.

Task-number: QTBUG-58296
Change-Id: Ibddec795cdadedef7e17d22c265c29e752d8f99f
Reviewed-by: Olivier Goffart (Woboq GmbH) <ogoffart@woboq.com>

1 files changed, 21 insertions, 1 deletions

diff --git a/src/corelib/kernel/qvariant_p.h b/src/corelib/kernel/qvariant_p.h
index bf88def438..487949431c 100644
--- a/src/corelib/kernel/qvariant_p.h
+++ b/src/corelib/kernel/qvariant_p.h
@@ -177,6 +177,26 @@ inline void v_clear(QVariant::Private *d, T* = 0)
 
 }
 
+template <typename T>
+struct PrimitiveIsNull
+{
+public:
+    static bool isNull(const QVariant::Private *d)
+    {
+        return d->is_null;
+    }
+};
+
+template <>
+struct PrimitiveIsNull<std::nullptr_t>
+{
+public:
+    static bool isNull(const QVariant::Private *)
+    {
+        return true;
+    }
+};
+
 template<class Filter>
 class QVariantComparator {
     template<typename T, bool IsAcceptedType = Filter::template Acceptor<T>::IsAccepted>
@@ -268,7 +288,7 @@ class QVariantIsNull
     {
         static bool isNull(const QVariant::Private *d)
         {
-            return d->is_null;
+            return PrimitiveIsNull<T>::isNull(d);
         }
     };