QVBoxLayout* buttonLayout = new QVBoxLayout;

    QPushButton *button = new QPushButton;
    button->setStyleSheet("border : 1px solid gray;"
                          "background: transparent;");
    button->setFixedSize(64,64);

    QLabel* iconLabel = new QLabel();
    iconLabel->setTextInteractionFlags(Qt::NoTextInteraction);
    iconLabel->setPixmap(ip.icon(d).pixmap(16,16,QIcon::Normal, QIcon::On));
    iconLabel->setAlignment(Qt::AlignCenter);
    iconLabel->setStyleSheet("border : 0px");
    QLabel* textLabel = new QLabel();
    textLabel->setTextInteractionFlags(Qt::NoTextInteraction);
    textLabel->setWordWrap(true);
    textLabel->setText(d.absoluteFilePath());
    textLabel->setAlignment(Qt::AlignCenter);
    textLabel->setStyleSheet("border : 0px;");

    buttonLayout->addWidget(iconLabel);
    buttonLayout->addWidget(textLabel);
    button->setLayout(buttonLayout);

    QObject::connect(button, &QPushButton::clicked, [this] () {
        Hi(d.absoluteFilePath());
    });
    quickLinks->addWidget(button);
}

@

You have to tell the lambda how to capture d.

Assuming d is a local variable:
@
(1) auto l = &d { // d is captured by reference };
(2) auto l = d { // d is captured by value };
(3) auto l = & { // all available variables are captured by reference };
(4) auto l = = { // all available variables are captured by value };
@

Or is d a member variable?

@struct MyClass
{
int foo() {
auto l = this{return d;};
return l();
};
int d {};
};@