C++ VS2013的Qt4到Qt5迁移链接器警告（和错误）

我有一个最初使用Qt4开发的项目，现在正致力于迁移到Qt5。经过几个小时的重新编写代码和删除新的不推荐调用后，我能够让项目进行编译，但现在我在让它链接时遇到了问题

我正在使用CMake生成项目文件。我首先修改“solutions”CMake文件并替换以下内容，从而开始迁移：

#############################################
# find QT
FIND_PACKAGE(Qt4 REQUIRED)

# configure QT modules
SET(QT_USER_QTCORE TRUE)
SET(QT_USE_QTMAIN TRUE)
SET(QT_USE_QTWEBKIT TRUE)
SET(QT_USE_QTNETWORK TRUE)
SET(QT_USE_QTSQL TRUE)

SET(QT_USE_QTXML TRUE)
SET(QT_USE_QTUITOOLS TRUE)

# include QT requirements
INCLUDE(${QT_USE_FILE})
ADD_DEFINITIONS(${QT_DEFINITIONS})
#############################################

使用（这需要清理）

在这之后，我注释掉了所有对

ADD_SUBDIRECTORY（）

的调用，并开始一次一个地将它们添加回来。我的项目使用，并且由于它对其他子目录没有其他依赖关系，所以它是我开始工作的第一个子项目

在Log4Qt的CMakeLists.txt文件中，我简单地将

QT4_WRAP_CPP（MOC_源文件${MOC_头文件}）

更改为

QT5_WRAP_CPP（MOC_源文件${MOC_头文件}）

，其中

MOC_头文件

被定义为Log4Qt中所有必要的MOC头文件

当我在VS2013和build中加载它时，它编译得很好，但是链接会为每个moc抛出相同的警告：

>moc_stringmatchfilter.obj : warning LNK4006: "public: static struct QMetaObject const Log4Qt::StringMatchFilter::staticMetaObject" (?staticMetaObject@StringMatchFilter@Log4Qt@@2UQMetaObject@@B) already defined in log4qt_automoc.obj; second definition ignored
>moc_stringmatchfilter.obj : warning LNK4006: "private: static void __cdecl Log4Qt::StringMatchFilter::qt_static_metacall(class QObject *,enum QMetaObject::Call,int,void * *)" (?qt_static_metacall@StringMatchFilter@Log4Qt@@CAXPEAVQObject@@W4Call@QMetaObject@@HPEAPEAX@Z) already defined in log4qt_automoc.obj; second definition ignored
>moc_stringmatchfilter.obj : warning LNK4006: "public: virtual struct QMetaObject const * __cdecl Log4Qt::StringMatchFilter::metaObject(void)const " (?metaObject@StringMatchFilter@Log4Qt@@UEBAPEBUQMetaObject@@XZ) already defined in log4qt_automoc.obj; second definition ignored
>moc_stringmatchfilter.obj : warning LNK4006: "public: virtual void * __cdecl Log4Qt::StringMatchFilter::qt_metacast(char const *)" (?qt_metacast@StringMatchFilter@Log4Qt@@UEAAPEAXPEBD@Z) already defined in log4qt_automoc.obj; second definition ignored
>moc_stringmatchfilter.obj : warning LNK4006: "public: virtual int __cdecl Log4Qt::StringMatchFilter::qt_metacall(enum QMetaObject::Call,int,void * *)" (?qt_metacall@StringMatchFilter@Log4Qt@@UEAAHW4Call@QMetaObject@@HPEAPEAX@Z) already defined in log4qt_automoc.obj; second definition ignored
>moc_stringmatchfilter.obj : warning LNK4221: This object file does not define any previously undefined public symbols, so it will not be used by any link operation that consumes this library

我继续迁移，并继续收到相同的警告。例如，以下是其中一个子项目的完整CMakeLists.txt文件：

项目（网络）

包含目录（${CMAKE\u CURRENT\u BINARY\u DIR}）

设置（源文件RequestCache.cpp WebClient.cpp）

SET（MOC_HEADERS RequestCache.h WebClient.h）

集合（头文件${MOC\u头文件}）

设置（依赖项列表log4qt核心）

添加\u库（网络静态${SOURCE\u FILES}${HEADER\u FILES} ${MOC_源文件}）

QT5_使用_模块（网络）

以及(部分)警告:

moc_WebClient.obj : warning LNK4006: "public: virtual struct QMetaObject const * __cdecl owl::WebClient::metaObject(void)const " (?metaObject@WebClient@owl@@UEBAPEBUQMetaObject@@XZ) already defined in Network_automoc.obj; second definition ignored
moc_WebClient.obj : warning LNK4006: "public: virtual void * __cdecl owl::WebClient::qt_metacast(char const *)" (?qt_metacast@WebClient@owl@@UEAAPEAXPEBD@Z) already defined in Network_automoc.obj; second definition ignored
moc_WebClient.obj : warning LNK4006: "public: virtual int __cdecl owl::WebClient::qt_metacall(enum QMetaObject::Call,int,void * *)" (?qt_metacall@WebClient@owl@@UEAAHW4Call@QMetaObject@@HPEAPEAX@Z) already defined in Network_automoc.obj; second definition ignored
moc_WebClient.obj : warning LNK4006: "private: static void __cdecl owl::WebClient::qt_static_metacall(class QObject *,enum QMetaObject::Call,int,void * *)" (?qt_static_metacall@WebClient@owl@@CAXPEAVQObject@@W4Call@QMetaObject@@HPEAPEAX@Z) already defined in Network_automoc.obj; second definition ignored
moc_WebClient.obj : warning LNK4006: "public: static struct QMetaObject const owl::WebClient::staticMetaObject" (?staticMetaObject@WebClient@owl@@2UQMetaObject@@B) already defined in Network_automoc.obj; second definition ignored
moc_WebClient.obj : warning LNK4221: This object file does not define any previously undefined public symbols, so it will not be used by any link operation that consumes this library

尽管如此，我还是继续添加了所有相关的项目，并试图构建项目的可执行文件。然后我得到了以下错误（可执行文件的项目名为“Owl”）（这是错误的摘录，而不是完整的列表）：

我做错了什么？我必须在我的CMake文件中修复此问题吗？我看不出我是如何错误地配置CMake的，还是我缺少了其他东西

---

谢谢大家!

感觉您没有正确清理项目生成目录。此外，如果您的CMake版本足够高，您可以尝试使用

CMake\u AUTOMOC

。更多细节。

我开了CMAKE_AUTOMOC，这是我的问题的一部分。我也在记录我的个人项目文件。我猜我是“双重MOC'ing”，因此链接器看到了每个MOC'd函数的两个定义。我尝试删除单个MOC呼叫，但这产生了另一个错误。所以，我关闭了automoc，这似乎解决了它！所以，你的回答引导我走向正确的方向！非常感谢你！！

moc_WebClient.obj : warning LNK4006: "public: virtual struct QMetaObject const * __cdecl owl::WebClient::metaObject(void)const " (?metaObject@WebClient@owl@@UEBAPEBUQMetaObject@@XZ) already defined in Network_automoc.obj; second definition ignored
moc_WebClient.obj : warning LNK4006: "public: virtual void * __cdecl owl::WebClient::qt_metacast(char const *)" (?qt_metacast@WebClient@owl@@UEAAPEAXPEBD@Z) already defined in Network_automoc.obj; second definition ignored
moc_WebClient.obj : warning LNK4006: "public: virtual int __cdecl owl::WebClient::qt_metacall(enum QMetaObject::Call,int,void * *)" (?qt_metacall@WebClient@owl@@UEAAHW4Call@QMetaObject@@HPEAPEAX@Z) already defined in Network_automoc.obj; second definition ignored
moc_WebClient.obj : warning LNK4006: "private: static void __cdecl owl::WebClient::qt_static_metacall(class QObject *,enum QMetaObject::Call,int,void * *)" (?qt_static_metacall@WebClient@owl@@CAXPEAVQObject@@W4Call@QMetaObject@@HPEAPEAX@Z) already defined in Network_automoc.obj; second definition ignored
moc_WebClient.obj : warning LNK4006: "public: static struct QMetaObject const owl::WebClient::staticMetaObject" (?staticMetaObject@WebClient@owl@@2UQMetaObject@@B) already defined in Network_automoc.obj; second definition ignored
moc_WebClient.obj : warning LNK4221: This object file does not define any previously undefined public symbols, so it will not be used by any link operation that consumes this library

error LNK2005: "public: static struct QMetaObject const owl::PostListWebView::staticMetaObject" (?staticMetaObject@PostListWebView@owl@@2UQMetaObject@@B) already defined in moc_PostListView.obj   C:\vbulletin\cmake\deltas\Win64\Deltas\Owl_automoc.obj  Owl
error LNK2005: "private: static void __cdecl owl::PostListWebView::qt_static_metacall(class QObject *,enum QMetaObject::Call,int,void * *)" (?qt_static_metacall@PostListWebView@owl@@CAXPEAVQObject@@W4Call@QMetaObject@@HPEAPEAX@Z) already defined in moc_PostListView.obj   C:\vbulletin\cmake\deltas\Win64\Deltas\Owl_automoc.obj  Owl
error LNK2005: "public: virtual struct QMetaObject const * __cdecl owl::BoardTreeView::metaObject(void)const " (?metaObject@BoardTreeView@owl@@UEBAPEBUQMetaObject@@XZ) already defined in moc_BoardTreeView.obj    C:\vbulletin\cmake\deltas\Win64\Deltas\Owl_automoc.obj  Owl
error LNK2005: "public: virtual void * __cdecl owl::BoardTreeView::qt_metacast(char const *)" (?qt_metacast@BoardTreeView@owl@@UEAAPEAXPEBD@Z) already defined in moc_BoardTreeView.obj C:\vbulletin\cmake\deltas\Win64\Deltas\Owl_automoc.obj  Owl
error LNK2005: "public: virtual int __cdecl owl::BoardTreeView::qt_metacall(enum QMetaObject::Call,int,void * *)" (?qt_metacall@BoardTreeView@owl@@UEAAHW4Call@QMetaObject@@HPEAPEAX@Z) already defined in moc_BoardTreeView.obj    C:\vbulletin\cmake\deltas\Win64\Deltas\Owl_automoc.obj  Owl
error LNK2005: "private: static void __cdecl owl::BoardTreeView::qt_static_metacall(class QObject *,enum QMetaObject::Call,int,void * *)" (?qt_static_metacall@BoardTreeView@owl@@CAXPEAVQObject@@W4Call@QMetaObject@@HPEAPEAX@Z) already defined in moc_BoardTreeView.obj  C:\vbulletin\cmake\deltas\Win64\Deltas\Owl_automoc.obj  Owl
error LNK2005: "public: virtual struct QMetaObject const * __cdecl owl::ConfiguringBoardDlg::metaObject(void)const " (?metaObject@ConfiguringBoardDlg@owl@@UEBAPEBUQMetaObject@@XZ) already defined in moc_ConfiguringBoardDlg.obj  C:\vbulletin\cmake\deltas\Win64\Deltas\Owl_automoc.obj  Owl
error LNK2005: "public: virtual void * __cdecl owl::ConfiguringBoardDlg::qt_metacast(char const *)" (?qt_metacast@ConfiguringBoardDlg@owl@@UEAAPEAXPEBD@Z) already defined in moc_ConfiguringBoardDlg.obj   C:\vbulletin\cmake\deltas\Win64\Deltas\Owl_automoc.obj  Owl