Qt6 desktop app and shared library with cmake - c++

Question

I am trying to make a project with subdirectories using cmake.
When using qmake this mechanism was built in Qt creator.
The project contains a shared library and a desktop app.
Below is the structure of the project and cmake I have:
Main cmake:
cmake_minimum_required (VERSION 3.5)
project(contractapp)
add_subdirectory(contract-core)
add_subdirectory(contract-desktop)
Desktop app cmake:
project(contract-desktop LANGUAGES CXX)
set(CMAKE_INCLUDE_CURRENT_DIR ON)
set(CMAKE_AUTOUIC ON)
set(CMAKE_AUTOMOC ON)
set(CMAKE_AUTORCC ON)
set(CMAKE_CXX_STANDARD 17)
set(CMAKE_CXX_STANDARD_REQUIRED ON)
# QtCreator supports the following variables for Android, which are identical to qmake Android variables.
# Check https://doc.qt.io/qt/deployment-android.html for more information.
# They need to be set before the find_package( ...) calls below.
#if(ANDROID)
# set(ANDROID_PACKAGE_SOURCE_DIR "${CMAKE_CURRENT_SOURCE_DIR}/android")
# if (ANDROID_ABI STREQUAL "armeabi-v7a")
# set(ANDROID_EXTRA_LIBS
# ${CMAKE_CURRENT_SOURCE_DIR}/path/to/libcrypto.so
# ${CMAKE_CURRENT_SOURCE_DIR}/path/to/libssl.so)
# endif()
#endif()
find_package(QT NAMES Qt6 Qt5 COMPONENTS Widgets REQUIRED)
find_package(Qt${QT_VERSION_MAJOR} COMPONENTS Widgets REQUIRED)
find_package(contract-core REQUIRED)
set(PROJECT_SOURCES
main.cpp
MainWindow.cpp
MainWindow.h
MainWindow.ui
)
if(${QT_VERSION_MAJOR} GREATER_EQUAL 6)
qt_add_executable(contract-desktop
${PROJECT_SOURCES}
)
else()
if(ANDROID)
add_library(contract-desktop SHARED
${PROJECT_SOURCES}
)
else()
add_executable(contract-desktop
${PROJECT_SOURCES}
)
endif()
endif()
target_link_libraries(contract-desktop PRIVATE Qt${QT_VERSION_MAJOR}::Widgets)
Shared library cmake:
cmake_minimum_required(VERSION 3.14)
project(contract-core LANGUAGES CXX)
set(CMAKE_INCLUDE_CURRENT_DIR ON)
set(CMAKE_AUTOUIC ON)
set(CMAKE_AUTOMOC ON)
set(CMAKE_AUTORCC ON)
set(CMAKE_CXX_STANDARD 17)
set(CMAKE_CXX_STANDARD_REQUIRED ON)
find_package(QT NAMES Qt6 Qt5 COMPONENTS Core REQUIRED)
find_package(Qt${QT_VERSION_MAJOR} COMPONENTS Core REQUIRED)
add_library(contract-core SHARED
contract-core_global.h
Person.cpp
Person.h
)
target_link_libraries(contract-core PRIVATE Qt${QT_VERSION_MAJOR}::Core)
target_compile_definitions(contract-core PRIVATE CONTRACTCORE_LIBRARY)
My problem is that the desktop application does not see the library that I am making.

Answer 1

That library has to be copied to the same folder the application is in. Otherwise, each is in its own folder, and the application won't see it. Most likely you'd want to set the target folder for both binaries (the application and the library) to be some common build subfolder of both.