demo

demo/test_widget/main.cpp

+#include "widget.h"
+
+#include <QApplication>
+
+int main(int argc, char *argv[])
+{
+    QApplication a(argc, argv);
+    Widget w;
+    w.show();
+    return a.exec();
+}

demo/test_widget/test_widget.pro

+QT       += core gui
+
+greaterThan(QT_MAJOR_VERSION, 4): QT += widgets
+
+CONFIG += c++11
+
+# The following define makes your compiler emit warnings if you use
+# any Qt feature that has been marked deprecated (the exact warnings
+# depend on your compiler). Please consult the documentation of the
+# deprecated API in order to know how to port your code away from it.
+DEFINES += QT_DEPRECATED_WARNINGS
+
+# You can also make your code fail to compile if it uses deprecated APIs.
+# In order to do so, uncomment the following line.
+# You can also select to disable deprecated APIs only up to a certain version of Qt.
+#DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000    # disables all the APIs deprecated before Qt 6.0.0
+
+SOURCES += \
+    main.cpp \
+    widget.cpp
+
+HEADERS += \
+    widget.h
+
+# Default rules for deployment.
+qnx: target.path = /tmp/$${TARGET}/bin
+else: unix:!android: target.path = /opt/$${TARGET}/bin
+!isEmpty(target.path): INSTALLS += target

demo/test_widget/widget.cpp

+#include "widget.h"
+
+Widget::Widget(QWidget *parent)
+    : QWidget(parent)
+{
+}
+
+Widget::~Widget()
+{
+}
+

demo/test_widget/widget.h

+#ifndef WIDGET_H
+#define WIDGET_H
+
+#include <QWidget>
+#include <QPushButton>
+
+
+class Widget : public QWidget
+{
+    Q_OBJECT
+
+public:
+    Widget(QWidget *parent = nullptr);
+    ~Widget();
+};
+#endif // WIDGET_H