具体背景

使用QT Creator进行编译运行，出现如下错误：

-1: error: LNK2019: unresolved external symbol “public: void __thiscall MainWindow::actionChanged(void)” (?actionChanged@MainWindow@@QAEXXZ) referenced in function “private: static void __cdecl MainWindow::qt_static_metacall(class QObject -1: e