cmake¶

Minimal CMakeLists.txt¶

cmake_minimum_required(VERSION 3.10)
set(CMAKE_CXX_STANDARD 17)
set(CMAKE_CXX_STANDARD_REQUIRED True)
project(example)
add_executable(a.out a.cpp b.cpp)

Wildcard Sourse Files¶

cmake_minimum_required(VERSION 3.10)
set(CMAKE_CXX_STANDARD 17)
set(CMAKE_CXX_STANDARD_REQUIRED True)
file(GLOB src "*.cpp")

project(example)
add_executable(a.out ${src})

Set CXXFLAGS¶

cmake_minimum_required(VERSION 3.10)
set(CMAKE_CXX_STANDARD 17)
set(CMAKE_CXX_STANDARD_REQUIRED True)
file(GLOB src "*.cc")

project(example)
set(CMAKE_CXX_FLAGS "-Wall -Werror -O3")
add_executable(a.out ${src})

cmake_minimum_required(VERSION 3.10)
set(CMAKE_CXX_STANDARD 17)
set(CMAKE_CXX_STANDARD_REQUIRED True)
file(GLOB src "*.cc")

project(example)
add_executable(a.out ${src})
target_compile_options(a.out PRIVATE -Werror)

Set CXXFLAGS with Build Type¶

# common
set(CMAKE_CXX_FLAGS "-Wall -Werror -O3")
# debug
set(CMAKE_CXX_FLAGS_DEBUG "${CMAKE_CXX_FLAGS} -g")
# release
set(CMAKE_C_FLAGS_RELEASE "${CMAKE_CXX_FLAGS} -O3 -pedantic")

Build Debug/Release¶

$ cmake -DCMAKE_BUILD_TYPE=Release ../
$ cmake -DCMAKE_BUILD_TYPE=Debug ../

Build with Type¶

cmake_minimum_required(VERSION 3.10)
set(CMAKE_CXX_STANDARD 17)
set(CMAKE_CXX_STANDARD_REQUIRED True)
project(example)
add_executable(a.out a.cc)

if(CMAKE_BUILD_TYPE STREQUAL "Debug")
  target_compile_options(a.out PRIVATE -g -O0 -Wall)
else()
  target_compile_options(a.out PRIVATE -O3 -Wall -Werror)
endif()

Instead of checking CMAKE_BUILD_TYPE, modern CMake prefers to use generator expressions to examine conditions.

cmake_minimum_required(VERSION 3.10)
set(CMAKE_CXX_STANDARD 17)
set(CMAKE_CXX_STANDARD_REQUIRED True)
project(example)
add_executable(a.out a.cc)
target_compile_options(a.out PRIVATE
  $<IF:$<CONFIG:Debug>, -g -O0 -Wall, -O3 -Wall -Werror>
)

Version File¶

cmake_minimum_required(VERSION 3.10)
set(CMAKE_CXX_STANDARD 17)
set(CMAKE_CXX_STANDARD_REQUIRED True)
file(GLOB src "*.cpp")

project(example VERSION 1.0)
configure_file(version.h.in version.h)

add_executable(a.out ${src})
target_include_directories(a.out PUBLIC "${PROJECT_BINARY_DIR}")

version.h.in

#pragma once

#define VERSION_MAJOR @example_VERSION_MAJOR@
#define VERSION_MINOR @example_VERSION_MINOR@

Build/Link a static library¶

cmake_minimum_required(VERSION 3.10)
set(CMAKE_CXX_STANDARD 17)
set(CMAKE_CXX_STANDARD_REQUIRED True)
file(GLOB src "*.cpp")

project(example VERSION 1.0)
configure_file(version.h.in version.h)

add_executable(a.out ${src})
add_library(b b.cpp)
target_link_libraries(a.out PUBLIC b)
target_include_directories(a.out PUBLIC "${PROJECT_BINARY_DIR}")

Build/Link a shared library¶

cmake_minimum_required(VERSION 3.10)
set(CMAKE_CXX_STANDARD 17)
set(CMAKE_CXX_STANDARD_REQUIRED True)
file(GLOB src "*.cpp")

project(example VERSION 1.0)
configure_file(version.h.in version.h)

add_executable(a.out ${src})
add_library(b SHARED b.cpp)
target_link_libraries(a.out PUBLIC b)
target_include_directories(a.out PUBLIC "${PROJECT_BINARY_DIR}")

Subdirectory¶

subdirectory fib/

cmake_minimum_required(VERSION 3.10)
set(CMAKE_CXX_STANDARD 17)
set(CMAKE_CXX_STANDARD_REQUIRED True)
file(GLOB src "*.cpp")
add_library(b SHARED b.cpp)
target_include_directories(b PUBLIC "${CMAKE_CURRENT_SOURCE_DIR}")

project dir

cmake_minimum_required(VERSION 3.10)
set(CMAKE_CXX_STANDARD 17)
set(CMAKE_CXX_STANDARD_REQUIRED True)
file(GLOB src "*.cpp")

project(example VERSION 1.0)
configure_file(version.h.in version.h)

add_executable(a.out ${src})
add_subdirectory(fib)
target_link_libraries(a.out PUBLIC b)
target_include_directories(a.out PUBLIC
    "${PROJECT_BINARY_DIR}"
    "${PROJECT_BINARY_DIR/fib}"
)

PUBLIC & PRIVATE¶

PUBLIC - only affect the current target, not dependencies
INTERFACE - only needed for dependencies

cmake_minimum_required(VERSION 3.10)

project(example)
set(CMAKE_CXX_STANDARD 17)
set(CMAKE_CXX_STANDARD_REQUIRED True)
find_package(Boost)

add_executable(a.out a.cpp)
add_library(b STATIC b.cpp b.h)

target_include_directories(a.out PRIVATE "${CMAKE_CURRENT_SOURCE_DIR}")
target_include_directories(b PRIVATE "${Boost_INCLUDE_DIR}")
target_link_libraries(a.out INTERFACE b) # link b failed

Generator Expression¶

cmake_minimum_required(VERSION 3.10)
set(CMAKE_CXX_STANDARD 17)
set(CMAKE_CXX_STANDARD_REQUIRED True)
project(example)

set(target fib)
add_library(${target} src/fib.cc)
target_compile_options(${target} PRIVATE -Wall -Werror -Wextra)
target_include_directories(${target}
  PUBLIC
    $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include>
    $<INSTALL_INTERFACE:include>
  PRIVATE
    ${CMAKE_CURRENT_SOURCE_DIR}/src
)

Install¶

cmake_minimum_required(VERSION 3.10)
project(a)
add_library(b_static STATIC b.cc)
add_library(b_shared SHARED b.cc)
add_executable(a a.cc b.cc)

include(GNUInstallDirs)
set(INSTALL_TARGETS a b_static b_shared)
install(TARGETS ${INSTALL_TARGETS}
  ARCHIVE DESTINATION ${CMAKE_INSTALL_LIBDIR}
  LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR}
  RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR}
)
install(FILES b.h DESTINATION ${CMAKE_INSTALL_INCLUDEDIR})

Run a command at configure time¶

execute_process(
    COMMAND git submodule update --init --recursive
    WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}
    RESULT_VARIABLE GIT_SUBMOD_RESULT
)

Option¶

# $ make -p build
# $ cd build
# $ cmake -DBUILD_TEST=ON ../

option(BUILD_TEST "Build test" OFF)
if (BUILD_TEST)
    message("Build tests.")
else()
    message("Ignore tests.")
endif()

Alias a Library¶

When a CMakeLists.txt export Foo in namespace Foo::, it also need to create an alias Foo::Foo.

add_library(Foo::Foo ALIAS Foo)