CMake building library and executable once and linking it - c++

Question

I'm trying to build two projects using cmake at same-time.
My folder structure is as follows:
project
├── CMakeLists.txt
├── build
├── out
├── lib
├── yanthra_engine
│  ├── CMakeLists.txt
│   └── ...
└───sandbox
├── CMakeLists.txt
└── ...
main CmakeLists.txt
cmake_minimum_required(VERSION 3.4.1)
project(yanthra_console VERSION 0.1 DESCRIPTION "A 3d Game Engine.")
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++17 -fexceptions")
set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
set(CMAKE_CONFIGURATION_TYPES "RelWithDebInfo;Release;Debug" CACHE STRING "Build type selections" FORCE)
add_subdirectory(yanthra_engine)
add_subdirectory(sandbox)
yanthra_engine/CMakeLists.txt
set(THIRD_PARTY_DIR "../../../third-party")
set(MAIN_SOURCE_DIR "../../main/src")
include_directories(${THIRD_PARTY_DIR}/SDL/include)
set(CMAKE_LIBRARY_OUTPUT_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}/../lib )
set(CMAKE_ARCHIVE_OUTPUT_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}/../lib)
file(GLOB_RECURSE CPP_HEADERS ${MAIN_SOURCE_DIR}/*.hpp)
file(GLOB_RECURSE CPP_SOURCES ${MAIN_SOURCE_DIR}/*.cpp)
add_library(
yanthra
SHARED
${CPP_HEADERS}
${CPP_SOURCES}
)
set (CMAKE_SHARED_LINKER_FLAGS "-F../yanthra_engine/Frameworks -framework SDL2 -framework OpenGL")
sandbox/CMakeLists.txt
set(THIRD_PARTY_DIR "../../main")
set(MAIN_SOURCE_DIR "./src")
include_directories(${THIRD_PARTY_DIR}/include)
set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}/../out)
file(GLOB_RECURSE CPP_HEADERS ${MAIN_SOURCE_DIR}/includes/*.h)
file(GLOB_RECURSE CPP_SOURCES ${MAIN_SOURCE_DIR}/*.cpp)
file(GLOB_RECURSE LIB ${MAIN_SOURCE_DIR}/../lib/*.dylib)
add_executable(
yanthra_sandbox
${CPP_HEADERS}
${CPP_SOURCES}
)
set_target_properties(
yanthra_sandbox
PROPERTIES
LINK_FLAGS
"-F../yanthra_engine/Frameworks -framework SDL2 -framework OpenGL"
)
target_link_libraries(yanthra_sandbox PRIVATE ${LIB})
I would like to know if I'm generating library file in each build mode, how will I link it with it's corresponding executable, given the fact that each mode builds its output to to its own folder i.e for library its lib/Debug (for debug mode) and for executable its out/Debug.

Answer 1

You don't seem to link the link the yanthra target. You should do this though, since this will automatically choose the library compiled with the current configuration.
sandbox/CMakeLists.txt
...
target_link_libraries(yanthra_sandbox PRIVATE yanthra ${LIB})
...
As for importing the other libs: It would be preferrable to use find_library. This should automatically set the link options and make adding them for yanthra_sandbox unnecessary.
yanthra_engine/CMakeLists.txt
...
list(APPEND CMAKE_FRAMEWORK_PATH "${CMAKE_CURRENT_SOURCE_DIR}/Frameworks")
find_library(SDL2_LIB SDL2 REQUIRED)
find_library(OPEN_GL_LIB OpenGL REQUIRED)
target_link_library(yanthra PUBLIC "${SDL2_LIB}" "${OPEN_GL_LIB}")
This should allow you to remove the compiler flags from both targets. If there are no dependencies in the lib directory you could also remove the search for the libraries on the file system/