链接时出现CMake错误
我是CMake的新手，我正试着用它来构建一个小的KDE应用程序。我不得不使用QTXml模块，我的程序编译没有问题，但在链接阶段，我找不到QXml组件…
main.cpp
#include "test.h"
int main(int argc, char **argv)
{
return 0;
}test.h
#ifndef TEST_H
#define TEST_H
#include <QXmlResultItems>
#include <QString>
#include <QBuffer>
#include <QXmlQuery>
class test {
public:
test(){}
~test(){}
QXmlResultItems* find ( const QString& node, const QString& xpath );
private:
QBuffer device_;
};
#endif // TEST_Htest.cpp
#include "test.h"
QXmlResultItems* test::find ( const QString& node, const QString& xpath )
{
QXmlResultItems* result = new QXmlResultItems;
QXmlQuery query;
query.bindVariable ( "device",&device_ );
query.setQuery ( "doc($device)/"+node+"/"+xpath );
query.evaluateTo ( result );
return result;
}CMakeLists.cmake
project(qtcmakepb)
find_package(KDE4 REQUIRED)
include (KDE4Defaults)
include_directories( ${KDE4_INCLUDES} ${QT_INCLUDES} )
#Supposed to be useless because of KDE4 REQUIRED and ${QT_INCLUDES}
find_package(Qt4 COMPONENTS QtCore QtXml REQUIRED )
# In this CMakeLists.txt we define which files
# are used to compile the application
set(qtcmakepb_SRCS main.cpp test.cpp)
# Set the name of the application
kde4_add_executable(qtcmakepb ${qtcmakepb_SRCS})
# Select which libraries we need to link to
target_link_libraries(qtcmakepb ${KDE4_KDEUI_LIBS})
target_link_libraries(qtcmakepb ${QT_QTCORE_LIBS})
target_link_libraries(qtcmakepb ${QT_QTXML_LIBS})
# Tell cmake to install the application binary
install(TARGETS qtcmakepb ${INSTALL_TARGETS_DEFAULT_ARGS})
# Install the .desktop file
install( PROGRAMS qtcmakepb.desktop DESTINATION ${XDG_APPS_INSTALL_DIR} )make的输出：
Linking CXX executable qtcmakepb
CMakeFiles/qtcmakepb.dir/test.o: In function `test::find(QString const&, QString const&)':
/home/zelwina/projects/QtCmakePb/src/test.cpp:5: undefined reference to `QXmlResultItems::QXmlResultItems()'
/home/zelwina/projects/QtCmakePb/src/test.cpp:6: undefined reference to `QXmlQuery::QXmlQuery()'
/home/zelwina/projects/QtCmakePb/src/test.cpp:7: undefined reference to `QXmlQuery::bindVariable(QString const&, QIODevice*)'
/home/zelwina/projects/QtCmakePb/src/test.cpp:8: undefined reference to `QXmlQuery::setQuery(QString const&, QUrl const&)'
/home/zelwina/projects/QtCmakePb/src/test.cpp:9: undefined reference to `QXmlQuery::evaluateTo(QXmlResultItems*) const'
/home/zelwina/projects/QtCmakePb/src/test.cpp:10: undefined reference to `QXmlQuery::~QXmlQuery()'
collect2: erreur: ld a retourné 1 code d'état d'exécution
make[2]: *** [src/qtcmakepb] Erreur 1
make[1]: *** [src/CMakeFiles/qtcmakepb.dir/all] Erreur 2
make: *** [all] Erreur 2我做错了什么？
回答 3
Stack Overflow用户
发布于 2012-06-20 00:06:53
要使用CMake的FindQt4 module，请执行以下操作：
find_package(Qt4 COMPONENTS QtCore QtXml REQUIRED)
include(${QT_USE_FILE})
include_directories(${KDE4_INCLUDES} ${QT_INCLUDES})
target_link_libraries(qtcmakepb ${KDE4_KDEUI_LIBS} ${QT_LIBRARIES})如果要指定单独的包含目录和库，请将上面的最后两行替换为：
include_directories(${KDE4_INCLUDES}
${QT_QTCORE_INCLUDE_DIR}
${QT_QTXML_INCLUDE_DIR})
target_link_libraries(qtcmakepb
${KDE4_KDEUI_LIBS}
${QT_QTCORE_LIBRARY}
${QT_QTXML_LIBRARY})您的问题是您没有调用include(${QT_USE_FILE})，而QT_QTCORE_LIBS应该是QT_QTCORE_LIBRARY (对于QtXml库也是如此)。此外，您需要在调用FindQt4模块和included QT_USE_FILE之后调用include_directories。
有关随您的CMake版本提供的FindQt4模块的完整信息，请运行：
cmake --help-module FindQt4编辑
事实证明，根本原因实际上是未定义的函数是QtXmlPatterns库的一部分，因此find_package调用应该在列表中包含QtXmlPatterns。
完成后，通过调用include(${QT_USE_FILE})设置变量${QT_QTXMLPATTERNS_INCLUDE_DIR}和${QT_QTXMLPATTERNS_LIBRARY}，并可以根据需要添加它们。
如果使用的是QT5，则为
有了Qt5，使用CMake变得更简单了。
为了包含和链接QtXml和QtXmlPatterns，您只需要以下几行：
find_package(Qt5Xml REQUIRED)
find_package(Qt5XmlPatterns REQUIRED)并按如下方式链接：
target_link_libraries(qtcmakepb Qt5::Xml Qt5::XmlPatterns)Stack Overflow用户
发布于 2012-06-19 21:53:27
您启用QT_USE_QTXML了吗？
尝试：set(QT_USE_QTXML TRUE)
Stack Overflow用户
发布于 2012-06-19 22:38:09
不知道这是否有帮助，但是：
target_link_libraries(qtcmakepb ${QT_QTCORE_LIBS})
target_link_libraries(qtcmakepb ${QT_QTXML_LIBS})您需要使用以下代码：
target_link_libraries(qtcmakepb ${QT_LIBRARIES})这会将您选择的所有内容与find_package(Qt4)中的COMPONENTS子句链接起来。Cave-at:如果您将多个目标与不同的Qt组件集链接在一起，这将不起作用。
https://stackoverflow.com/questions/11102151
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