#include <QApplication>
#include <QJsonDocument>
#include <QJsonObject>

#include <cmath>

int main(int argc, char *argv[])
{
    QJsonDocument doc = QJsonDocument::fromJson("{\"test\":-0}");
    QJsonObject obj = doc.object();
    auto d = obj.value("test").toDouble();

    // Expected to be "true"
    qDebug() << "Sign bit: " << std::signbit(d);

    d = -0;
    obj.insert("test", d);
    doc.setObject(obj);

    // Expected to be {"test":-0}
    qDebug() << "Resulting JSON: " << doc.toJson(QJsonDocument::Compact);
    return 0;
}