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/io/qdatastream.h b/src/corelib/io/qdatastream.h
index db1bbfbd63..575607e147 100644
--- a/src/corelib/io/qdatastream.h
+++ b/src/corelib/io/qdatastream.h
@@ -152,6 +152,7 @@ public:
     QDataStream &operator>>(quint32 &i);
     QDataStream &operator>>(qint64 &i);
     QDataStream &operator>>(quint64 &i);
+    QDataStream &operator>>(std::nullptr_t &ptr) { ptr = nullptr; return *this; }
 
     QDataStream &operator>>(bool &i);
     QDataStream &operator>>(qfloat16 &f);
@@ -167,6 +168,7 @@ public:
     QDataStream &operator<<(quint32 i);
     QDataStream &operator<<(qint64 i);
     QDataStream &operator<<(quint64 i);
+    QDataStream &operator<<(std::nullptr_t) { return *this; }
     QDataStream &operator<<(bool i);
     QDataStream &operator<<(qfloat16 f);
     QDataStream &operator<<(float f);