Add a means to send a POST request that has an empty body

Actually this has already worked if a nullptr was casted as a
QIODevice*. Add an overload with a nullptr_t type, that does
this behind the scenes.

Fixes: QTBUG-108309
Change-Id: I2d4b17ae94cf4de2c42257d471ef901c8994fee5
Reviewed-by: Juha Vuolle <juha.vuolle@qt.io>
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>

src/network/access/qnetworkaccessmanager.cpp

@@ -856,6 +856,24 @@ QNetworkReply *QNetworkAccessManager::post(const QNetworkRequest &request, const
     return reply;
 }
 
+/*!
+    \overload
+
+    \since 6.8
+
+    Sends the POST request specified by \a request without a body and returns
+    a new QNetworkReply object.
+*/
+QNetworkReply *QNetworkAccessManager::post(const QNetworkRequest &request, std::nullptr_t nptr)
+{
+    Q_UNUSED(nptr);
+    QIODevice *dev = nullptr;
+
+    return d_func()->postProcess(createRequest(QNetworkAccessManager::PostOperation,
+                                               request,
+                                               dev));
+}
+
 #if QT_CONFIG(http) || defined(Q_OS_WASM)
 /*!
     \since 4.8

src/network/access/qnetworkaccessmanager.h

@@ -84,6 +84,7 @@ public:
     QNetworkReply *get(const QNetworkRequest &request, const QByteArray &data);
     QNetworkReply *post(const QNetworkRequest &request, QIODevice *data);
     QNetworkReply *post(const QNetworkRequest &request, const QByteArray &data);
+    QNetworkReply *post(const QNetworkRequest &request, std::nullptr_t nptr);
     QNetworkReply *put(const QNetworkRequest &request, QIODevice *data);
     QNetworkReply *put(const QNetworkRequest &request, const QByteArray &data);
     QNetworkReply *deleteResource(const QNetworkRequest &request);

tests/auto/network/access/qnetworkreply/tst_qnetworkreply.cpp

@@ -270,6 +270,8 @@ private Q_SLOTS:
     void postToHttpMultipart_data();
     void postToHttpMultipart();
     void multipartSkipIndices(); // QTBUG-32534
+    void postWithoutBody_data();
+    void postWithoutBody();
 #if QT_CONFIG(ssl)
     void putToHttps_data();
     void putToHttps();
@@ -646,6 +648,7 @@ public:
 
     bool stopTransfer = false;
     bool checkedContentLength = false;
+    bool foundContentLength = false;
     int contentRead = 0;
     int contentLength = 0;
 
@@ -677,6 +680,7 @@ public:
     {
         contentLength = 0;
         receivedData.clear();
+        foundContentLength = false;
     }
 
 protected:
@@ -737,6 +741,8 @@ private:
         if (index == -1)
             return;
 
+        foundContentLength = true;
+
         index += sizeof("content-length:") - 1;
         const auto end = std::find(receivedData.cbegin() + index, receivedData.cend(), '\r');
         auto num = receivedData.mid(index, std::distance(receivedData.cbegin() + index, end));
@@ -3062,6 +3068,47 @@ void tst_QNetworkReply::multipartSkipIndices() // QTBUG-32534
     multiPart->deleteLater();
 }
 
+void tst_QNetworkReply::postWithoutBody_data()
+{
+    QTest::addColumn<bool>("client_data");
+
+    QTest::newRow("client_has_data") << true;
+    QTest::newRow("client_does_not_have_data") << false;
+}
+
+void tst_QNetworkReply::postWithoutBody()
+{
+    QFETCH(bool, client_data);
+
+    QBuffer buff;
+
+    if (client_data) {
+        buff.setData("Dummy data from client to server");
+        buff.open(QIODevice::ReadOnly);
+    }
+
+    QByteArray dataFromServerToClient = QByteArray("Some ridiculous dummy data");
+    QByteArray httpResponse = QByteArray("HTTP/1.0 200 OK\r\nContent-Length: ");
+    httpResponse += QByteArray::number(dataFromServerToClient.size());
+    httpResponse += "\r\n\r\n";
+    httpResponse += dataFromServerToClient;
+
+    MiniHttpServer server(httpResponse);
+    server.doClose = true;
+
+    QNetworkRequest request(QUrl("http://localhost:" + QString::number(server.serverPort())));
+    request.setHeader(QNetworkRequest::ContentTypeHeader, QVariant("text/plain"));
+
+    QNetworkReplyPtr reply;
+    if (client_data)
+        reply.reset(manager.post(request, &buff));
+    else
+        reply.reset(manager.post(request, nullptr));
+
+    QVERIFY2(waitForFinish(reply) == Success, msgWaitForFinished(reply));
+    QCOMPARE(server.foundContentLength, client_data);
+}
+
 void tst_QNetworkReply::putToHttpMultipart_data()
 {
     postToHttpMultipart_data();