Can't compile project using CLion and CMake

mingvv

Hello, Qt community!
I’m new to programming, especially in Qt. So please don’t swear if I write anything stupid.
Now I’m trying to install and create the first Qt project. I am using CLion with CMake and Qt 6.
I set up CMake:

cmake_minimum_required(VERSION 3.17)
project(QSnake)

set(CMAKE_CXX_STANDARD 20)
set(CMAKE_AUTOMOC ON)
set(CMAKE_AUTORCC ON)
set(CMAKE_AUTOUIC ON)

set(QT_VERSION 6)
set(REQUIRED_LIBS Core Gui Widgets)
set(REQUIRED_LIBS_QUALIFIED Qt6::Core Qt6::Gui Qt6::Widgets)

set(CMAKE_PREFIX_PATH D:/Qt/6.0.2/mingw81_64/lib/cmake)

add_executable(${PROJECT_NAME} main.cpp)

if(NOT CMAKE_PREFIX_PATH)
    message(WARNING "CMAKE_PREFIX_PATH is not defined, you may need to set it "
                    "(-DCMAKE_PREFIX_PATH=\"path/to/Qt/lib/cmake\" or -DCMAKE_PREFIX_PATH=/usr/include/{host}/qt{version}/ on Ubuntu)")
endif()
#D:\Qt\6.0.2\mingw81_64\lib\cmake
find_package(Qt${QT_VERSION} COMPONENTS ${REQUIRED_LIBS} REQUIRED)
target_link_libraries(${PROJECT_NAME} ${REQUIRED_LIBS_QUALIFIED})
if(WIN32)
    set(DEBUG_SUFFIX)
    if (CMAKE_BUILD_TYPE MATCHES "Debug")
        set(DEBUG_SUFFIX "d")
    endif()
    set(QT_INSTALL_PATH "${CMAKE_PREFIX_PATH}")
    if(NOT EXISTS "${QT_INSTALL_PATH}/bin")
        set(QT_INSTALL_PATH "${QT_INSTALL_PATH}/..")
        if(NOT EXISTS "${QT_INSTALL_PATH}/bin")
            set(QT_INSTALL_PATH "${QT_INSTALL_PATH}/..")
        endif()
    endif()
    if(EXISTS "${QT_INSTALL_PATH}/plugins/platforms/qwindows${DEBUG_SUFFIX}.dll")
        add_custom_command(TARGET ${PROJECT_NAME} POST_BUILD
                COMMAND ${CMAKE_COMMAND} -E make_directory
                "$<TARGET_FILE_DIR:${PROJECT_NAME}>/plugins/platforms/")
        add_custom_command(TARGET ${PROJECT_NAME} POST_BUILD
                COMMAND ${CMAKE_COMMAND} -E copy
                "${QT_INSTALL_PATH}/plugins/platforms/qwindows${DEBUG_SUFFIX}.dll"
                "$<TARGET_FILE_DIR:${PROJECT_NAME}>/plugins/platforms/")
    endif()
    foreach(QT_LIB ${REQUIRED_LIBS})
        add_custom_command(TARGET ${PROJECT_NAME} POST_BUILD
                COMMAND ${CMAKE_COMMAND} -E copy
                "${QT_INSTALL_PATH}/bin/Qt${QT_VERSION}${QT_LIB}${DEBUG_SUFFIX}.dll"
                "$<TARGET_FILE_DIR:${PROJECT_NAME}>")
    endforeach(QT_LIB)
endif()

Actually, this is how it was generated when the CLion project was created. I only set the path: D:/Qt/6.0.2/mingw81_64/lib/cmake

Just in case, I will also add the main.c code. It is also generated by CLion.

#include <QApplication>
#include <QPushButton>

int
main(int argc,
     char *argv[])
{
    QApplication a(argc, argv);
    QPushButton button("Hello world!", nullptr);
    button.resize(200, 100);
    button.show();
    return QApplication::exec();
}

I don’t see any problems with CMake, but when I try to run the project there is an error:

Error copying file "D:/Qt/6.0.2/mingw81_64/lib/cmake/../../bin/Qt6Cored.dll" to "D:/QSnake/cmake-build-debug".
mingw32-make[3]: *** [CMakeFiles\QSnake.dir\build.make:126: QSnake.exe] Error 1
mingw32-make[3]: *** Deleting file 'QSnake.exe'
mingw32-make[2]: *** [CMakeFiles\Makefile2:96: CMakeFiles/QSnake.dir/all] Error 2
mingw32-make[1]: *** [CMakeFiles\Makefile2:103: CMakeFiles/QSnake.dir/rule] Error 2
mingw32-make: *** [Makefile:137: QSnake] Error 2

Can you please tell me what this is about? I guess I haven’t set something up or pointed out a way?

SGaist

Hi and welcome to devnet,

@mingvv said in Can't compile project using CLion and CMake:

Qt6Cored.dll

Where do you have that file in your Qt 6 installation ?

mingvv

Problem solved.
Whether it is useful to anyone, but the CMake automatically generated by CLion contains rows that cause an error in debug mode (adds 'd' suffix to all dll files):

if (CMAKE_BUILD_TYPE MATCHES "Debug")
    set(DEBUG_SUFFIX "d")
endif()

Deleting those lines saved me :)

nagesh

@mingvv during debug it will link with debug version of the dll.
eg:QtCored.dll

Christian Ehrlicher

@mingvv said in Can't compile project using CLion and CMake:

Deleting those lines saved me :)

I don't see why this would help anything.

mingvv

@nagesh Maybe I don't have debug dll?

Christian Ehrlicher

Since you can't mix (msvc) / should not (mingw) debug and release libs it's dangerous to use Qt release dlls with a debug build of your program.
And this strang install stuff is not needed at all - use windeployqt

mingvv

@Christian-Ehrlicher said in Can't compile project using CLion and CMake:

Since you can't mix (msvc) / should not (mingw) debug and release libs it's dangerous to use Qt release dlls with a debug build of your program.

Where can I get debug dll files? I reinstalled Qt, but it didn’t help. Are they at another address?

@Christian-Ehrlicher said in Can't compile project using CLion and CMake:

And this strang install stuff is not needed at all - use windeployqt

What does it do? This utility helps configure Qt for Windows?

And then there’s the question. Can I run Qt project (CMake) using Visual Studio?

jsulm

@mingvv said in Can't compile project using CLion and CMake:

What does it do?

It deploys Qt applications. See https://doc.qt.io/qt-5/windows-deployment.html

Qt debug libs are installed together with release libs if you use Qt Online Installer/Maintenance Tool.

mingvv

@jsulm Yes, but using QtCreator I can simply build and launch the project during the development phase. With other IDE to build Qt I cannot. So I’m not sure if this windeployqt.exe is what I need. Maybe I just don’t understand why I need to... But my current goal is simply to build a project using at least Visual Studio.

jsulm

@mingvv said in Can't compile project using CLion and CMake:

With other IDE to build Qt I cannot

OK, then this is indeed another issue.
If you're using Visual Studio then this line is wrong:

set(CMAKE_PREFIX_PATH D:/Qt/6.0.2/mingw81_64/lib/cmake)

It should point to Qt for Visual Studio, not for MinGW.

mingvv

@jsulm said in Can't compile project using CLion and CMake:

@mingvv said in Can't compile project using CLion and CMake:

With other IDE to build Qt I cannot

OK, then this is indeed another issue.
If you're using Visual Studio then this line is wrong:
set(CMAKE_PREFIX_PATH D:/Qt/6.0.2/mingw81_64/lib/cmake)
It should point to Qt for Visual Studio, not for MinGW.

I only have this folder. Using MaintenanceTool.exe I also don't see separate components for MSVC.

I used CMake GUI app to generate projects and solution (.sln), but while trying to compile I have 18 errors in library files. Is that why I have MinGW in CMake?

jsulm

@mingvv said in Can't compile project using CLion and CMake:

Using MaintenanceTool.exe I also don't see separate components for MSVC

You should. You could try to reinstall Qt.

mingvv

@jsulm
Indeed, it has now been possible to install the MSVC version. I have upgraded CMake, but this has not corrected the bugs in the project build:

2>main.obj : error LNK2019: unresolved external symbol "__declspec(dllimport) public: __cdecl QString::~QString(void)" (__imp_??1QString@@QEAA@XZ) referenced in function main
2>main.obj : error LNK2019: unresolved external symbol "__declspec(dllimport) public: __cdecl QString::QString(char const *)" (__imp_??0QString@@QEAA@PEBD@Z) referenced in function main
2>main.obj : error LNK2019: unresolved external symbol "__declspec(dllimport) public: __cdecl QApplication::QApplication(int &,char * *,int)" (__imp_??0QApplication@@QEAA@AEAHPEAPEADH@Z) referenced in function main
2>main.obj : error LNK2019: unresolved external symbol "__declspec(dllimport) public: virtual __cdecl QApplication::~QApplication(void)" (__imp_??1QApplication@@UEAA@XZ) referenced in function main
2>main.obj : error LNK2019: unresolved external symbol "__declspec(dllimport) public: static int __cdecl QApplication::exec(void)" (__imp_?exec@QApplication@@SAHXZ) referenced in function main
2>main.obj : error LNK2019: unresolved external symbol "__declspec(dllimport) public: void __cdecl QWidget::show(void)" (__imp_?show@QWidget@@QEAAXXZ) referenced in function main
2>main.obj : error LNK2019: unresolved external symbol "__declspec(dllimport) public: void __cdecl QWidget::resize(int,int)" (__imp_?resize@QWidget@@QEAAXHH@Z) referenced in function main
2>main.obj : error LNK2019: unresolved external symbol "__declspec(dllimport) public: __cdecl QPushButton::QPushButton(class QString const &,class QWidget *)" (__imp_??0QPushButton@@QEAA@AEBVQString@@PEAVQWidget@@@Z) referenced in function main
2>main.obj : error LNK2019: unresolved external symbol "__declspec(dllimport) public: virtual __cdecl QPushButton::~QPushButton(void)" (__imp_??1QPushButton@@UEAA@XZ) referenced in function main
2>main.obj : error LNK2001: unresolved external symbol "public: virtual __cdecl QApplication::~QApplication(void)" (??1QApplication@@UEAA@XZ)
2>main.obj : error LNK2001: unresolved external symbol "public: virtual __cdecl QPushButton::~QPushButton(void)" (??1QPushButton@@UEAA@XZ)
2>main.obj : error LNK2001: unresolved external symbol "public: __cdecl QString::~QString(void)" (??1QString@@QEAA@XZ)
2>D:\QSnake\RelWithDebInfo\QSnake.exe : fatal error LNK1120: 12 unresolved externals

jsulm

@mingvv Did you try a complete rebuild?

mingvv

@jsulm Yes, I cleaned solution and rebuilt. Maybe I generated it wrong with CMake? Is there any build guide for Visual Studio or any hidden features?

Christian Ehrlicher

And make sure that the msvc libs are used during linking.

mingvv

Maybe I should add project additional include directories?

@Christian-Ehrlicher said in Can't compile project using CLion and CMake:

And make sure that the msvc libs are used during linking.

How can I check it? I guess I have default settings, because I didn't change them.

P.S. Maybe you know, after how many messages can I post more than once in 10 minutes?

Christian Ehrlicher

@mingvv said in Can't compile project using CLion and CMake:

How can I check it?

Since you've a msvc project take a look in the linker options. Or use cmake-gui to see the CMake values.

mingvv

@Christian-Ehrlicher If I correctly understood you, I use MSVC linker:
CMAKE_LINKER - C:/Program Files (x86)/Microsoft Visual Studio/2019/Community/VC/Tools/MSVC/14.28.29910/bin/Hostx64/x64/link.exe