I have a large CMake build using the Qt library. When I invoke this build on the command line or within VSCode, I found that the Qt5_DIR variable is not set in the cmake cache directly after configuring the project.
For example, after using the following command the Qt5_DIR is missing from the cache:
cmake -DQt5_DIR=C:/Qt/Qt5.12.12/5.12.12/msvc2017_64/lib/cmake/Qt5 -S .. -B .
This causes a problem if I later try to change a variable using the CMake GUI because I get an error about Qt5_DIR not being set. If I do set it explicitly in the CMake GUI, then the variable persists until I execute the command line version (or build within VSCode) again.
Is there a way I can get this variable to persist when cmake is invoked on the command line?
*Tested using CMake 3.24.3 and 3.31.4.
Update: I reproduced this problem in a very simple project
Create CMakeLists.txt and fill it with the following code:
cmake_minimum_required(VERSION 3.24)
project(testprog)
variable_watch("Qt5_DIR")
if(POLICY CMP0020)
cmake_policy(SET CMP0020 NEW)
endif()
if(POLICY CMP0043)
cmake_policy(SET CMP0043 NEW)
endif()
#necessary for QT stuff
set(CMAKE_INCLUDE_CURRENT_DIR ON)
set(CMAKE_AUTOMOC ON)
set(CMAKE_AUTORCC ON)
find_package(Qt5 COMPONENTS Widgets Core SerialPort QML Quick LinguistTools Sql REQUIRED)
#set qt5 include dirs as 'system' dirs
include_directories(SYSTEM ${Qt5Widgets_INCLUDE_DIRS})
include_directories(.)
qt5_wrap_ui(UI_HEADERS
mainwindow.ui)
SET(PROG_SOURCES
mainwindow.cpp
main.cpp
${UI_HEADERS}
)
add_executable(testprog WIN32 ${PROG_SOURCES})
qt5_use_modules(testprog Widgets Core SerialPort QuickWidgets Sql)
Create the following files in the folder with CMakeLists.txt (they can be empty): main.cpp mainwindow.cpp mainwindow.ui
Create a sub-folder called 'build' and change directory to there.
On the command line from within 'build' run the following cmake command:
cmake "-DCMAKE_CONFIGURATION_TYPES=Debug;Release;MinSizeRel;RelWithDebInfo" -DQt5_DIR=C:/Qt/Qt5.12.12/5.12.12/msvc2017_64/lib/cmake/Qt5 -G "Visual Studio 17 2022" -A x64 ..
Which produces the following output:
-- Selecting Windows SDK version 10.0.22621.0 to target Windows 10.0.19045.
-- The C compiler identification is MSVC 19.41.34123.0
-- The CXX compiler identification is MSVC 19.41.34123.0
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working C compiler: C:/Program Files/Microsoft Visual Studio/2022/Community/VC/Tools/MSVC/14.41.34120/bin/Hostx64/x64/cl.exe - skipped
-- Detecting C compile features
-- Detecting C compile features - done
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Check for working CXX compiler: C:/Program Files/Microsoft Visual Studio/2022/Community/VC/Tools/MSVC/14.41.34120/bin/Hostx64/x64/cl.exe - skipped
-- Detecting CXX compile features
-- Detecting CXX compile features - done
CMake Debug Log at CMakeLists.txt:21 (find_package):
Variable "Qt5_DIR" was accessed using READ_ACCESS with value
"C:/Qt/Qt5.12.12/5.12.12/msvc2017_64/lib/cmake/Qt5".
CMake Debug Log at CMakeLists.txt:21 (find_package):
Variable "Qt5_DIR" was accessed using READ_ACCESS with value
"C:/Qt/Qt5.12.12/5.12.12/msvc2017_64/lib/cmake/Qt5".
-- Configuring done (4.0s)
-- Generating done (0.2s)
-- Build files have been written to: C:/Users/Documents/git/testcmakeqt/build
Observe cache contents
cmake -L
which shows that Qt5_DIR is missing:
-- Cache values
CMAKE_INSTALL_PREFIX:PATH=C:/Program Files/testprog
Qt5Core_DIR:PATH=C:/Qt/Qt5.12.12/5.12.12/msvc2017_64/lib/cmake/Qt5Core
Qt5Gui_DIR:PATH=C:/Qt/Qt5.12.12/5.12.12/msvc2017_64/lib/cmake/Qt5Gui
Qt5LinguistTools_DIR:PATH=C:/Qt/Qt5.12.12/5.12.12/msvc2017_64/lib/cmake/Qt5LinguistTools
Qt5Network_DIR:PATH=C:/Qt/Qt5.12.12/5.12.12/msvc2017_64/lib/cmake/Qt5Network
Qt5QML_DIR:PATH=C:/Qt/Qt5.12.12/5.12.12/msvc2017_64/lib/cmake/Qt5Qml
Qt5Qml_DIR:PATH=C:/Qt/Qt5.12.12/5.12.12/msvc2017_64/lib/cmake/Qt5Qml
Qt5QuickWidgets_DIR:PATH=C:/Qt/Qt5.12.12/5.12.12/msvc2017_64/lib/cmake/Qt5QuickWidgets
Qt5Quick_DIR:PATH=C:/Qt/Qt5.12.12/5.12.12/msvc2017_64/lib/cmake/Qt5Quick
Qt5SerialPort_DIR:PATH=C:/Qt/Qt5.12.12/5.12.12/msvc2017_64/lib/cmake/Qt5SerialPort
Qt5Sql_DIR:PATH=C:/Qt/Qt5.12.12/5.12.12/msvc2017_64/lib/cmake/Qt5Sql
Qt5Widgets_DIR:PATH=C:/Qt/Qt5.12.12/5.12.12/msvc2017_64/lib/cmake/Qt5Widgets
Configure the project using the CMake GUI instead and observe that Qt5_DIR is still present after specifying it there.
cmake -L
output:
-- Cache values
CMAKE_BACKWARDS_COMPATIBILITY:STRING=2.4
CMAKE_CONFIGURATION_TYPES:STRING=Debug;Release;MinSizeRel;RelWithDebInfo
CMAKE_INSTALL_PREFIX:PATH=C:/Program Files/Project
EXECUTABLE_OUTPUT_PATH:PATH=
LIBRARY_OUTPUT_PATH:PATH=
Qt5Core_DIR:PATH=C:/Qt/Qt5.12.12/5.12.12/msvc2017_64/lib/cmake/Qt5Core
Qt5Gui_DIR:PATH=C:/Qt/Qt5.12.12/5.12.12/msvc2017_64/lib/cmake/Qt5Gui
Qt5LinguistTools_DIR:PATH=C:/Qt/Qt5.12.12/5.12.12/msvc2017_64/lib/cmake/Qt5LinguistTools
Qt5Network_DIR:PATH=C:/Qt/Qt5.12.12/5.12.12/msvc2017_64/lib/cmake/Qt5Network
Qt5QML_DIR:PATH=C:/Qt/Qt5.12.12/5.12.12/msvc2017_64/lib/cmake/Qt5Qml
Qt5Qml_DIR:PATH=C:/Qt/Qt5.12.12/5.12.12/msvc2017_64/lib/cmake/Qt5Qml
Qt5QuickWidgets_DIR:PATH=C:/Qt/Qt5.12.12/5.12.12/msvc2017_64/lib/cmake/Qt5QuickWidgets
Qt5Quick_DIR:PATH=C:/Qt/Qt5.12.12/5.12.12/msvc2017_64/lib/cmake/Qt5Quick
Qt5SerialPort_DIR:PATH=C:/Qt/Qt5.12.12/5.12.12/msvc2017_64/lib/cmake/Qt5SerialPort
Qt5Sql_DIR:PATH=C:/Qt/Qt5.12.12/5.12.12/msvc2017_64/lib/cmake/Qt5Sql
Qt5Widgets_DIR:PATH=C:/Qt/Qt5.12.12/5.12.12/msvc2017_64/lib/cmake/Qt5Widgets
Qt5_DIR:PATH=C:/Qt/Qt5.12.12/5.12.12/msvc2017_64/lib/cmake/Qt5