使用 Qt 对 vtable 的未定义引用

Posted 2023-03-30

【中文标题】使用 Qt 对 vtable 的未定义引用

【英文标题】：Undefined reference to vtable using Qt

【发布时间】：2021-11-30 22:18:32

【问题描述】：

我是 Qt 新手，我正在尝试做一个简单的 VoIP 应用程序。 我使用 CMake 和 conan 来获取所有包并构建应用程序。如果我将所有与 Qt 相关的类头文件和源文件放在同一个目录中，我可以毫无问题地编译，但是当我将头文件移动到另一个目录时，我发现链接器有问题。我不知道为什么，因为在 CMakeLists.txt 中我声明了包含目录（并且对于与 Qt 无关的其他类也可以正常工作），我觉得这与 autoMOC 有关。

项目结构

|--include
|     |
|     |--client
|     |    |
|     |    |--views
|     |    |    |
|     |    |    |--loginwindow.ui
|     |    |    |--ui_loginwindow.h
|     |    |    |--mainwindow.ui
|     |    |    |--ui_mainwindow.h
|     |    |--Client.h
|     |    |--loginWindow.h
|     |    |--mainWindow.h
|     |    |--Profile.h
|     |--common
|     |
|     |--server
|     |
|--src
|   |
|   |--client
|   |   |
|   |   |--Controller
|   |   |--Model
|   |   |--View
|   |   |    |
|   |   |    |--loginWindow.cpp
|   |   |    |--mainWindow.cpp
|   |--common
|   |
|   |--server
|   |

我省略了一些目录内容，因为那里没有发现问题。

CMakeLists.txt

if ($CMAKE_SOURCE_DIR STREQUAL $CMAKE_BINARY_DIR)
    message(FATAL_ERROR "Prevented in-tree built. Please create a build directory outside of the source code and call cmake from there")
endif ()

list(APPEND CMAKE_MODULE_PATH $CMAKE_BINARY_DIR)
list(APPEND CMAKE_PREFIX_PATH $CMAKE_BINARY_DIR)

project(babel)
cmake_minimum_required(VERSION 3.17.4)

set(CMAKE_CXX_STANDARD 17)
set(CMAKE_CXX_STANDARD_REQUIRED ON)

add_definitions("-fPIC")

if(MSVC)
    set(CMAKE_EXE_LINKER_FLAGS "$CMAKE_EXE_LINKER_FLAGS")
else()
    set(STANDARD_UNIX_CXX_FLAGS "-Wall -g3 -Wextra -Wfatal-errors")
    set(CMAKE_CXX_FLAGS "$CMAKE_CXX_FLAGS $STANDARD_UNIX_CXX_FLAGS")
endif()

if (EXISTS $CMAKE_BINARY_DIR/conanbuildinfo.cmake)
    include($CMAKE_BINARY_DIR/conanbuildinfo.cmake)
else()
    message(FATAL_ERROR "No conanbuildinfo.cmake file found")
endif()

conan_basic_setup(KEEP_RPATHS)

set(CMAKE_INCLUDE_CURRENT_DIR ON)
set(CMAKE_AUTOMOC ON)
set(CMAKE_AUTORCC ON)
set(CMAKE_AUTOUIC ON)

find_package(Qt5OpenGL CONFIG REQUIRED)
find_package(Qt5Widgets CONFIG REQUIRED)
find_package(Qt5Core CONFIG REQUIRED)
find_package(Qt5Gui CONFIG REQUIRED)
find_package(Qt5Network CONFIG REQUIRED)
find_package(portaudio REQUIRED)
find_package(Opus REQUIRED)
find_package(asio REQUIRED)

file(
        GLOB_RECURSE
        SOURCES_CLIENT
        $PROJECT_SOURCE_DIR/src/*.cpp
        $PROJECT_SOURCE_DIR/src/client/*.cpp
        $PROJECT_SOURCE_DIR/include/client/*.hpp
        $PROJECT_SOURCE_DIR/include/client/*.ui
        $PROJECT_SOURCE_DIR/resources.qrc
)
file(
        GLOB_RECURSE
        SOURCES_SERVER
        $PROJECT_SOURCE_DIR/src/server/*.cpp
)
file(
        GLOB_RECURSE
        SOURCES_COMMON
        $PROJECT_SOURCE_DIR/src/common/*.cpp
        $PROJECT_SOURCE_DIR/include/common/*.hpp
)
add_executable(babel_client $SOURCES_CLIENT $SOURCES_COMMON)
install(TARGETS babel_client DESTINATION $PROJECT_SOURCE_DIR/bin)
target_link_libraries(
        babel_client
        Qt5::Widgets
        Qt5::Network
        Qt5::OpenGL
        Qt5::Core
        Qt5::Gui
        opus
        portaudio
)
target_include_directories(
        babel_client PRIVATE
        $CONAN_INCLUDE_LIBS
        $PROJECT_SOURCE_DIR/include/client
        $PROJECT_SOURCE_DIR/include/client/views
        $PROJECT_SOURCE_DIR/include/common
)

loginWindow.h

#ifndef LOGINWINDOW_H
#define LOGINWINDOW_H

#include <QMainWindow>
#include "mainWindow.h"
#include "views/ui_loginwindow.h"
#include <QKeyEvent>

QT_BEGIN_NAMESPACE
namespace Ui  class LoginWindow; 
QT_END_NAMESPACE

class LoginWindow : public QMainWindow

    Q_OBJECT

public:
    LoginWindow(QWidget *parent = nullptr);
    ~LoginWindow();

private slots:
    void on_loginButton_clicked();

protected:
    void keyPressEvent(QKeyEvent *key);

private:
    Ui::LoginWindow *ui;
    MainWindow *mainWindow;
;
#endif // LOGINWINDOW_H

loginWindow.cpp

#include "loginWindow.h"
#include <QPixmap>

LoginWindow::LoginWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::LoginWindow)

    int picWidth;
    int picHeight;

    ui->setupUi(this);
    QPixmap pix(":/resources/babel.png");
    picWidth = ui->babelPicture->width();
    picHeight = ui->babelPicture->height();
    ui->babelPicture->setPixmap(pix.scaled(picWidth, picHeight, Qt::KeepAspectRatio));
    ui->statusbar->addPermanentWidget(ui->statusText);
    ui->loginButton->setDefault(true);


LoginWindow::~LoginWindow()

    delete (ui);


void LoginWindow::keyPressEvent(QKeyEvent *key)

    if (key->key() == Qt::Key_Return)
        on_loginButton_clicked();


void LoginWindow::on_loginButton_clicked()

    QString user = ui->userField->text();
    QString pass = ui->passwordField->text();

    if (user == "test" && pass == "test") 
        ui->statusText->setText("Correct login");
        this->hide();
        mainWindow = new MainWindow(this);
        mainWindow->show();
     else
        ui->statusText->setText("Inorrect login");
    

mainWindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include "views/ui_mainwindow.h"

namespace Ui 
class MainWindow;


class MainWindow : public QMainWindow

    Q_OBJECT

public:
    explicit MainWindow(QWidget *parent = nullptr);
    ~MainWindow();

private:
    Ui::MainWindow *ui;
;

#endif // MAINWINDOW_H

mainWindow.cpp

#include "mainWindow.h"

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)

    ui->setupUi(this);


MainWindow::~MainWindow()

    delete ui;

链接器输出

/usr/bin/ld: CMakeFiles/babel_client.dir/src/client/View/loginWindow.cpp.o: in function `LoginWindow::~LoginWindow()':
/home/bltksk/epitech/tek3/CPP/babel/src/client/View/loginWindow.cpp:20: undefined reference to `vtable for LoginWindow'
/usr/bin/ld: CMakeFiles/babel_client.dir/src/client/View/loginWindow.cpp.o: in function `non-virtual thunk to LoginWindow::~LoginWindow()':
/home/bltksk/epitech/tek3/CPP/babel/src/client/View/loginWindow.cpp:23: undefined reference to `vtable for LoginWindow'
/usr/bin/ld: CMakeFiles/babel_client.dir/src/client/View/loginWindow.cpp.o: in function `LoginWindow::LoginWindow(QWidget*)':
/home/bltksk/epitech/tek3/CPP/babel/src/client/View/loginWindow.cpp:6: undefined reference to `vtable for LoginWindow'
/usr/bin/ld: CMakeFiles/babel_client.dir/src/client/View/mainWindow.cpp.o: in function `MainWindow::MainWindow(QWidget*)':
/home/bltksk/epitech/tek3/CPP/babel/src/client/View/mainWindow.cpp:5: undefined reference to `vtable for MainWindow'
/usr/bin/ld: CMakeFiles/babel_client.dir/src/client/View/mainWindow.cpp.o: in function `MainWindow::~MainWindow()':
/home/bltksk/epitech/tek3/CPP/babel/src/client/View/mainWindow.cpp:10: undefined reference to `vtable for MainWindow'
/usr/bin/ld: CMakeFiles/babel_client.dir/src/client/View/mainWindow.cpp.o: in function `non-virtual thunk to MainWindow::~MainWindow()':
/home/bltksk/epitech/tek3/CPP/babel/src/client/View/mainWindow.cpp:13: undefined reference to `vtable for MainWindow'

正如我在介绍中所说，如果我将 xxWindow.h 和 xxWindow.cpp 放在同一个文件夹中，问题就会消失，但是当我将它们放在包含目录中时，它不会链接。我不是 cmake 专家，但对我来说似乎是正确的。关于解决方案的任何提示？

【问题讨论】：

使用 GLOB 构造源文件列表是一种反模式。典型的失败模式是 CMake 看不到新文件。

【参考方案1】：

好的，我成功解决了问题。

为了使 AUTOUIC 正确运行，我们必须将所有包含 ui_*.h 的头文件添加到 sources 目标中，而不仅仅是包含路径。这样 automoc 将正确处理标头并正确链接。

在我的情况下是这样的：

file(
        GLOB_RECURSE
        SOURCES_CLIENT
        $PROJECT_SOURCE_DIR/src/*.cpp
        $PROJECT_SOURCE_DIR/src/client/*.cpp
        $PROJECT_SOURCE_DIR/include/client/*.h
        $PROJECT_SOURCE_DIR/include/client/resources/resources.qrc
)

另外，记得设置CMAKE_AUTOUIC_SEARCH_PATHS（cmake版本>3.9）为.ui文件所在的路径，否则会出现AutoUic错误。

我希望这对将来的人有所帮助。

【讨论】：

一个人不应该在没有CONFIGURE_DEPENDS的情况下使用GLOB_RECURSE，但最好不要使用它。