The relativeFilePath call is error in some case

#include <QDebug>
#include <QFile>
#include <QFileInfo>
#include <QDir>

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);
    QFile::link("../../b", "/home/alan/Desktop/b.link");
    qInfo() << QFileInfo("/home/alan/Desktop/b.link").symLinkTarget();    // result is "/home/b"  (This code is attempting to resolve to an absolute path. The function is documented as such.)

    QDir dir("/home/alan/Desktop/b.link");
    qInfo() << dir.relativeFilePath(QFileInfo("/home/alan/Desktop/b.link").symLinkTarget());  // result is "../../../b"  (It is not true, isn't it?)
}