I'm going crazy with QT6 and Cmake

arcy

Hi all! I'm trying to build my Windows Qt6 project with Cmake and without QTCreator, as an exercise. I'm building with Ninja generator. It builds correctly and I can find my .exe in the build directory. But when I run the executable I got an error that some Qt DLLs were not found (core, gui, quick and serialport). So I read this guide and tried to deploy with windeployqt, but at the end of the command execution I got "access denied". If I run my .exe with all DLLs copied in the build directory the error disappears but the app doesn't run...what I'm doing wrong?

My CmakeLists.txt:

cmake_minimum_required(VERSION 3.26)

project(prometheus_app VERSION 0.0.1 LANGUAGES CXX)

set(CMAKE_PREFIX_PATH "C:/Qt/6.5.0/mingw_64")
set(CMAKE_INCLUDE_CURRENT_DIR ON)

find_package(Qt6 REQUIRED COMPONENTS Gui Quick SerialPort)

qt_standard_project_setup(REQUIRES 6.5)

set(CMAKE_CXX_STANDARD 17)
set(CMAKE_CXX_STANDARD_REQUIRED ON)

qt_add_executable(prometheus src/main.cpp src/RtMidi.h src/RtMidi.cpp src/backend.h src/backend.cpp)

qt_add_qml_module(prometheus
    URI prometheus_app
    VERSION 1.0
    QML_FILES 
        ui/Main.qml
        ui/Fader.qml
)

target_link_libraries(prometheus PRIVATE Qt6::Gui Qt6::Quick Qt6::SerialPort setupapi Winmm)

set_target_properties(prometheus PROPERTIES WIN32_EXECUTABLE ON)

The windeployqt command:

.\windeployqt.exe C:\Users\arcid\dev\prometheus_cpp\build\prometheus.exe --qmldir C:\Users\arcid\dev\prometheus_cpp\ui

Thanks!

cristian-adam

Run DebugView before attempting to start your application.

You should see there some information why the application doesn't start.

From commandline you can set the environment variable set QT_LOGGING_RULES=qt*=true to get Qt to log things in DebugView.

Otherwise Event Viewer from Control Panel -> Windows Tools will log under Windows Logs -> Application details about processes that do not start.

And lastly Process Monitor logs all the file and registry access of a process.

Good luck in finding out why the application doesn't start 🤞

Axel Spoerl

@arcy
Just a bet in the dark, because I have fallen into the same trap many times:
The virus scanner doesn’t know the new executable, so it’s quarantined.
The build directory has to be excluded from scanning.

arcy

@Axel-Spoerl Hi and thanks for your reply, I configured my windows security by adding the built folder but it doesn't work. Maybe I have to set some environment variables?

Axel Spoerl

@arcy
Could you post the exact error message that appears when you try to launch the newly built executable, please?

arcy

@Axel-Spoerl I reinstall Qt and redo all from scratch. This is my CMakeLIsts.txt

cmake_minimum_required(VERSION 3.26)

project(prometheus_app VERSION 0.0.1 LANGUAGES CXX)

set(CMAKE_CXX_STANDARD 17)
set(CMAKE_CXX_STANDARD_REQUIRED ON)
set(CMAKE_PREFIX_PATH "C:/Qt/6.5.1/mingw_64")

find_package(Qt6 REQUIRED COMPONENTS Quick SerialPort)

qt_standard_project_setup()


qt_add_executable(prometheus WIN32 src/main.cpp src/RtMidi.h src/RtMidi.cpp src/backend.h src/backend.cpp)

qt_add_qml_module(prometheus
    URI prometheus_app
    VERSION 1.0
    QML_FILES ui/Main.qml ui/Fader.qml
)

add_definitions(-D__WINDOWS_MM__)

target_link_libraries(prometheus PRIVATE Qt6::Quick Qt6::SerialPort Winmm)

install(TARGETS prometheus
    BUNDLE DESTINATION .
    RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR}
)

qt_generate_deploy_app_script(
    TARGET prometheus
    OUTPUT_SCRIPT deployApp
)
install(SCRIPT "${deployApp}")

When I run

cmake -GNinja .. && ninja

it builds correctly, but when I run the .exe I get Qt6Qml.dll, Qt6Core.dll, Qt6Gui.dll and Qt6SerialPort.dll were not found. And this is my first problem because I can't debug my program.

So I tried to use windepolyqt.exe to copy all the DLLs needed inside my build folder, but when I run the .exe simply nothing happens...

Chris Kawa

@arcy said:

it builds correctly, but when I run the .exe I get Qt6Qml.dll, Qt6Core.dll, Qt6Gui.dll and Qt6SerialPort.dll were not found

Well yes. Building builds your exe. That exe needs the dependant Qt dlls to run, so you need to deploy those dlls to your app folder. You can copy them manually or use windeployqt to do it for you.

So I tried to use windepolyqt.exe to copy all the DLLs needed inside my build folder, but when I run the .exe simply nothing happens...

You need to give windeployqt the name of your exe as a command line argument.

arcy

@Chris-Kawa

.\windeployqt.exe C:\Users\arcid\dev\prometheus_cpp\build\prometheus.exe --qmldir C:\Users\arcid\dev\prometheus_cpp\ui

I guess I passed the exe as first argument

Chris Kawa

@arcy said:

but when I run the .exe simply nothing happens

Do you mean that nothing happens when you run windeployqt or nothing happens when you run your app after that?
Did windeployqt copy the dlls or not?

arcy

@Chris-Kawa
Nothing happens when I try to run the exe after the wideployqt command. All the needed dlls are correctly in the build folder.

Chris Kawa

@arcy Are the compiler runtime dlls also in your build directory? As with Qt dlls you can copy them manually or pass --compiler-runtime to windeployqt to do it for you.

arcy

@Chris-Kawa I re-run the windeployqt passing --compiler-runtime, my build folder now has this files:

But when I try to run prometheus.exe nothing happens... :-(

cristian-adam