CMake - Usual Build System

Question

After wrestling with CMake I now have a fully working solution. It works, however, I completely massacred the CMake File:

This is my main cmake file:

cmake_minimum_required(VERSION 3.17)
project(Odin)

include(ProcessorCount)
ProcessorCount(N)
if(NOT N EQUAL 0)
    set(CMAKE_BUILD_PARALLEL_LEVEL ${N})
endif()

message("Parallelizing with ${N} Cores")

set(CMAKE_CXX_STANDARD 17)
set(CMAKE_CXX_STANDARD_REQUIRED YES)
set(CMAKE_CXX_EXTENSIONS NO)

include_directories(Odin/engine)
include_directories(Odin/uci)
include_directories(Odin/util)
include_directories(Odin/util/iters)


# add our cmake modules under cmake/
list(APPEND CMAKE_MODULE_PATH "${PROJECT_SOURCE_DIR}/cmake")

# Include CPM dependency manager
include(CPM)


if(WIN64)
SET(BOOST_ROOT "C:/Program Files (x86)/boost/boost_1_74_0")
include_directories(${BOOST_ROOT})
include_directories(${BOOST_ROOT}/stage/lib)
endif()

find_package(Boost 1.74.0 REQUIRED serialization)

message(STATUS "---------------------")
message(STATUS "Boost_FOUND: ${Boost_FOUND}")
message(STATUS "Boost_INCLUDE_DIRS: ${Boost_INCLUDE_DIRS}")
message(STATUS "Boost_LIBRARY_DIRS: ${Boost_LIBRARY_DIRS}")
message(STATUS "Boost_LIBRARIES: ${Boost_LIBRARIES}")
message(STATUS "---------------------")

#EndBoost

add_executable(Odin
        Odin/engine/Odin.cc
        Odin/main.cc
        Odin/engine/Board.cc
        Odin/util/Utility.cc
        Odin/util/iters/BoardIterator.cc
        Odin/engine/Node.cc
        Odin/engine/Link.cc
        Odin/engine/Odin.h
        Odin/engine/Board.h
        Odin/engine/Figure.h
        Odin/util/Utility.h
        Odin/engine/Node.h
        Odin/engine/Link.h
        Odin/util/iters/BoardIterator.h)

add_library(Engine
        Odin/engine/Odin.cc
        Odin/main.cc
        Odin/engine/Board.cc
        Odin/util/Utility.cc
        Odin/util/iters/BoardIterator.cc
        Odin/engine/Node.cc
        Odin/engine/Link.cc
        Odin/engine/Odin.h
        Odin/engine/Board.h
        Odin/engine/Figure.h
        Odin/util/Utility.h
        Odin/engine/Node.h
        Odin/engine/Link.h
        Odin/util/iters/BoardIterator.h)


target_link_libraries(Engine PRIVATE Boost::serialization)
target_link_libraries(Odin PRIVATE Boost::serialization)

if(UNIX)
set(CMAKE_CXX_FLAGS "-O3 -march=native")
endif(UNIX)

#Make Tests
#enable testing
enable_testing()

# Pull doctest using CPM
cpmaddpackage("gh:onqtam/doctest#2.4.5")

# add the CMake modules for automatic test discovery so we can use
# doctest_discover_tests() CMake
set(CMAKE_MODULE_PATH "${doctest_SOURCE_DIR}/scripts/cmake"
        ${CMAKE_MODULE_PATH})


add_subdirectory(Testing)

To be honest, sometimes I had no idea what I was doing.

You see that I have to add every file into library and into the executable Odin. This is not that smart. I actually want my idea to still be able to add a .cpp file to the Odin - executable. However my test must still run, and they require me to add all the files twice.

You can find my tests (cmake) here: https://github.com/SuchtyTV/Odin/tree/master/Testing

Here are some questions:

• How do I walk around this library/executable non-sense?
• How do I ensure the Release build will be well optimized?
• Can I download Boost with CPM, if so, how would I do that and how would that look in the cmake file?
• Any other advices?

Answer 1

The code is mostly fine, however there are some problems:

SET(BOOST_ROOT "C:/Program Files (x86)/boost/boost_1_74_0")

^ This is wrong, because other developers may have Boost installed into different directory. Remove this line and let the user set BOOST_ROOT during configuration.

include_directories(${BOOST_ROOT})
include_directories(${BOOST_ROOT}/stage/lib)

^ Why is this required? The later find_package(Boost ...) call should set all required directories for you, which you can use in include_directories. This actually shouldn't be required at all, because linking to Boost using target_link_libraries should also set correct include directories.

add_executable(Odin ...
)

add_library(Engine ...
)

^ This looks wrong. First, you can remove code duplication by placing source files list into a variable:

set(SRCS ...
)

add_executable(Odin ${SRCS})
add_library(Engine ${SRCS})

Second, it looks strange that both library and executable consist of same source files. You probably want to keep most files being a part of the library and then link the library to executable. This is achieved by the same target_link_libraries command.

set(CMAKE_MODULE_PATH "${doctest_SOURCE_DIR}/scripts/cmake"
        ${CMAKE_MODULE_PATH})

^ Use list(APPEND ...), just like you did earlier in the code.