Cmake_Prefix_Path Doesn't Help Cmake in Finding Qt5

CMAKE_PREFIX_PATH doesn't help CMake in finding Qt5

I installed the following missing packages:

sudo apt-get install qtbase5-dev
sudo apt-get install qtdeclarative5-dev

Attaching any kind of prefix is not required now:

CMakeList:

    :~/junk/qtquick_hello_cmake$ cat CMakeLists.txt
    cmake_minimum_required(VERSION 2.8.12)
    
    project(qtquick_hello_cmake)
    
    set(CMAKE_INCLUDE_CURRENT_DIR ON)
    set(CMAKE_AUTOMOC ON)
    set(CMAKE_AUTORCC ON)
    
    find_package(Qt5 COMPONENTS Quick Core REQUIRED)
    
    qt5_add_resources(RESOURCES qml.qrc)
    
    add_executable(${PROJECT_NAME} "main.cpp" "qml.qrc")
    
    qt5_use_modules(${PROJECT_NAME} Quick Core)
    
    target_link_libraries(${PROJECT_NAME} Qt5::Core Qt5::Quick)

New output:

:~/junk/qtquick_hello_cmake$ ls
build  CMakeLists.txt  main.cpp  main.qml  qml.qrc

:~/junk/qtquick_hello_cmake$ cd build/
:~/junk/qtquick_hello_cmake/build$ rm -rf *

:~/junk/qtquick_hello_cmake/build$ cmake ../
-- The C compiler identification is GNU 4.8.4
-- The CXX compiler identification is GNU 4.8.4
-- Check for working C compiler: /usr/bin/cc
-- Check for working C compiler: /usr/bin/cc -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working CXX compiler: /usr/bin/c++
-- Check for working CXX compiler: /usr/bin/c++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Configuring done
-- Generating done
-- Build files have been written to: /home/.../junk/qtquick_hello_cmake/build

Errors are gone now.

Thanks to:

https://answers.ros.org/question/236324/could-not-find-a-package-configuration-file-provided-by-qt5widgets/

https://askubuntu.com/questions/508503/whats-the-development-package-for-qt5-in-14-04

CMAKE_PREFIX_PATH for Qt5

Since it has solved your question, I am just going to put it as an answer here. I will improve this section more in detail later.

If you are using cmake use find_package to find the package and then link to your
binary in later stage.

In order for find_package to be successful, Qt 5 must be found below the
CMAKE_PREFIX_PATH, or the Qt5_DIR must be set in the CMake cache to the 
location   of the Qt5Config.cmake file. The easiest way to use CMake is to set the
CMAKE_PREFIX_PATH environment variable to the install prefix of Qt 5.

If you just want to find the Qt modules then just set the Qt5_DIR
ex: Qt5_DIR="/Users/bob/Qt/5.12.7/clang_64/lib/cmake/Qt5"

when building with CMake you can use Qt5_DIR or CMAKE_PREFIX_PATH, both should work.

More explanation about building with CMake can be found here

cmake find_packages(QT5) does not use correct version of QT binaries despite setting prefix path

I figured it out...

This was a cmake cache issue most likely. I had thought It might have been this type of issue before, but I was clearing the wrong cmake version cache. I installed a different version of cmake on my computer (which is newer) than the one clion came with (I told it to use the default version i hadn't installed). So by deleting that cmake's cache it did absolutely nothing to my clion version of cmake (so IIRC from reading cmake docs, things like CMAKE_PREFIX_PATH would use cache versions by default) This made it impossible to switch off of anaconda version despite it, for example, when I put in the wrong version info IE find_package(Qt5 8.0 REQUIRED COMPONENTS Core Widgets Gui) clearly understanding and knowing the installation directory of the 5.8.0 directory (since it listed it):

Could not find a configuration file for package "Qt5" that is compatible
  with requested version "8".

  The following configuration files were considered but not accepted:

    C:/msys64/mingw64/lib/cmake/Qt5/Qt5Config.cmake, version: 5.8.0
    C:/ProgramData/Anaconda3/Library/lib/cmake/Qt5/Qt5Config.cmake, version: 5.6.2

Cmake couldn't let me use that version when I set the cmake path var, switching between both versions of cmake now builds correctly (i believe clion might clear cache when you switch from the internal version, I'm not sure). So hopefully any one else who happens upon this particular problem will now be able to fix it.

The tutorial actually working!

How to tell Cmake about Qt installation dir without changing PATH?

The reason your export CMAKE_PREFIX_PATH=... didn't work is that you passed the bin subdirectory instead of the installation prefix, as @vre already pointed out in the comments.

Alternatively, you can use -DQt5_ROOT=/Path/To/QtInstallationFolder/5.12.5/clang_64. I personally prefer to use these kind of package specific variables because in CI build scripts you can easily put them on separate lines which then don't become too long.

---

Related Topics