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, 20 insertions, 0 deletions

diff --git a/src/corelib/io/qdatastream.cpp b/src/corelib/io/qdatastream.cpp
index 2369fe4726..9a42fb4a37 100644
--- a/src/corelib/io/qdatastream.cpp
+++ b/src/corelib/io/qdatastream.cpp
@@ -771,6 +771,17 @@ int QDataStream::readBlock(char *data, int len)
 }
 
 /*!
+    \fn QDataStream &QDataStream::operator>>(std::nullptr &ptr)
+    \since 5.9
+    \overload
+
+    Simulates reading a \c{std::nullptr_t} from the stream into \a ptr and
+    returns a reference to the stream. This function does not actually read
+    anything from the stream, as \c{std::nullptr_t} values are stored as 0
+    bytes.
+*/
+
+/*!
     \fn QDataStream &QDataStream::operator>>(quint8 &i)
     \overload
 
@@ -1084,6 +1095,15 @@ int QDataStream::readRawData(char *s, int len)
   QDataStream write functions
  *****************************************************************************/
 
+/*!
+    \fn QDataStream &QDataStream::operator<<(std::nullptr ptr)
+    \since 5.9
+    \overload
+
+    Simulates writing a \c{std::nullptr_t}, \a ptr, to the stream and returns a
+    reference to the stream. This function does not actually write anything to
+    the stream, as \c{std::nullptr_t} values are stored as 0 bytes.
+*/
 
 /*!
     \fn QDataStream &QDataStream::operator<<(quint8 i)