CMake

Overview

Cmake is a Makefile generator.

It expects a configuration file named CMakeLists.txt at the root directory. We need to create a ephemeral directory (i.e. not to be committed), e.g. build/:

cd <project root>
mkdir build
cd build
cmake ..

This will not compile the code, but it does a bunch of checks, such as whether the listed files exist. It will generate the Makefile which we can then use to compile the code:

make

CMakeLists.txt

Template:

cmake_minimum_required(VERSION 3.15...3.30)

project(
    PetProject
    VERSION 1.0
    DESCRIPTION "My pet project"
    LANGUAGES CXX
)

add_library(mylib STATIC lib.cpp lib.h)

add_executable(binary main.cpp)
target_link_libraries(binary PUBLIC mylib)

Specifying C++ Standard Version

Equivalent to -std=20 in gcc/llvm.

set(CMAKE_CXX_STANDARD 20)
set(CMAKE_CXX_STANDARD_REQUIRED True)

Adding custom `make` subcommand

make run:

add_custom_target(run
    COMMAND binary  # i.e. ./binary
    DEPENDS binary  # target name
    WORKING_DIRECTORY ${CMAKE_SOURCE_DIR}
    COMMENT "runs binary"
)

Variables

Set:

set(MY_VAR "value")

Read:

set(MY_VAR "lib")
add_library(mylib STATIC ${MY_VAR}.cpp ${MY_VAR}.h)

List type: