QDataStream: add operator<< and >> for std::nullptr_t

std::nullptr_t is nullary: it accepts only one value, nullptr. So we
don't need to read or write anything. This commit simply adds the two
operators that allow generic code to operate on std::nullptr_t if
required.

This commit also adds the actual use to QMetaType::load/save, even
though there's no change in behavior.

[ChangeLog][QtCore][QDataStream] Added operator<< and operator>>
overloads that take std::nullptr_t, to facilitate generic code.

Change-Id: Iae839f6a131a4f0784bffffd14aa37e7f62d2740
Reviewed-by: Marc Mutz <marc.mutz@kdab.com>
Reviewed-by: Lars Knoll <lars.knoll@qt.io>

1 files changed, 2 insertions, 0 deletions

diff --git a/src/corelib/kernel/qmetatype.cpp b/src/corelib/kernel/qmetatype.cpp
index fc8d7dcfea..b75f2ad9dc 100644
--- a/src/corelib/kernel/qmetatype.cpp
+++ b/src/corelib/kernel/qmetatype.cpp
@@ -1350,6 +1350,7 @@ bool QMetaType::save(QDataStream &stream, int type, const void *data)
     case QMetaType::QJsonDocument:
         return false;
     case QMetaType::Nullptr:
+        stream << *static_cast<const std::nullptr_t *>(data);
         return true;
     case QMetaType::Long:
         stream << qlonglong(*static_cast<const long *>(data));
@@ -1573,6 +1574,7 @@ bool QMetaType::load(QDataStream &stream, int type, void *data)
     case QMetaType::QJsonDocument:
         return false;
     case QMetaType::Nullptr:
+        stream >> *static_cast<std::nullptr_t *>(data);
         return true;
     case QMetaType::Long: {
         qlonglong l;