CMake 옵션과 캐시 변수 — option·set·cache type 분석

1
set(MY_VAR "default" CACHE STRING "변수 설명")

1
# 예시
2
set(MY_INSTALL_PREFIX "/usr/local" CACHE PATH "Installation prefix")
3
set(ENABLE_TESTS ON CACHE BOOL "Enable unit tests")
4
set(VERSION_STRING "1.0.0" CACHE STRING "Version string")
5
set(DETECTED_COMPILER_PATH "/usr/bin/gcc" CACHE INTERNAL "")

1
# 첫 번째 cmake 실행: MY_VAR = "default"가 캐시에 저장됨
2
set(MY_VAR "default" CACHE STRING "")
3

4
# 사용자가 cmake -DMY_VAR=custom 으로 실행
5
# MY_VAR = "custom"
6

7
# 두 번째 cmake 실행: 캐시에 이미 있으므로 "default"로 덮어쓰지 않음
8
set(MY_VAR "default" CACHE STRING "")
9
# MY_VAR = "custom" 유지

1
set(MY_VAR "new_value" CACHE STRING "설명" FORCE)

1
option(ENABLE_TESTS "Enable unit tests" ON)
2

3
# 위 한 줄은 다음과 동치
4
set(ENABLE_TESTS ON CACHE BOOL "Enable unit tests")

1
set(MYAPP_BACKEND "OpenGL" CACHE STRING "Rendering backend")
2
set_property(CACHE MYAPP_BACKEND PROPERTY STRINGS OpenGL Vulkan DirectX)

1
# 기능 토글
2
option(ENABLE_TESTING "Enable unit tests" ON)
3
option(ENABLE_COVERAGE "Enable code coverage" OFF)
4
option(ENABLE_SANITIZERS "Enable sanitizers in Debug" ON)
5

6
# 빌드 방식
7
option(BUILD_SHARED_LIBS "Build shared libraries" OFF)
8
option(BUILD_DOCS "Build documentation" OFF)
9

10
# 의존성 선택
11
option(USE_SYSTEM_ZLIB "Use system zlib instead of bundled" OFF)
12
option(USE_SYSTEM_JSON "Use system nlohmann_json" OFF)

1
option(ENABLE_TESTING "Enable testing" ON)
2
option(USE_SYSTEM_ZLIB "Use system zlib" OFF)
3

4
if(ENABLE_TESTING)
5
    enable_testing()
6
    add_subdirectory(tests)
7
endif()
8

9
if(USE_SYSTEM_ZLIB)
10
    find_package(ZLIB REQUIRED)
11
    target_link_libraries(myapp PRIVATE ZLIB::ZLIB)
12
else()
13
    add_subdirectory(third_party/zlib)
14
    target_link_libraries(myapp PRIVATE zlib)
15
endif()

1
set(MY_VAR "cache_value" CACHE STRING "")
2
set(MY_VAR "normal_value")
3

4
message("${MY_VAR}")  # normal_value

1
set(MY_VAR "cache_value" CACHE STRING "")
2
set(MY_VAR "normal_value")
3

4
message("Cache: $CACHE{MY_VAR}")   # cache_value
5
message("Current: ${MY_VAR}")      # normal_value

1
include(CMakeDependentOption)
2

3
option(BUILD_TOOLS "Build tools" ON)
4

5
# BUILD_TOOLS가 ON일 때만 BUILD_TOOL_A를 선택할 수 있음
6
# BUILD_TOOLS가 OFF이면 BUILD_TOOL_A는 강제로 OFF
7
cmake_dependent_option(
8
    BUILD_TOOL_A "Build tool A" ON
9
    "BUILD_TOOLS" OFF
10
)
11

12
cmake_dependent_option(
13
    BUILD_TOOL_B "Build tool B" ON
14
    "BUILD_TOOLS" OFF
15
)

1
# ENABLE_TESTING이 ON이고 BUILD_SHARED_LIBS가 OFF일 때만 사용 가능
2
cmake_dependent_option(
3
    ENABLE_STATIC_TESTS "Static test builds" ON
4
    "ENABLE_TESTING;NOT BUILD_SHARED_LIBS" OFF
5
)

1
include(FeatureSummary)
2

3
option(ENABLE_FOO "Enable foo feature" ON)
4
option(ENABLE_BAR "Enable bar feature" OFF)
5
option(ENABLE_BAZ "Enable baz feature" ON)
6

7
add_feature_info(Foo ENABLE_FOO "The foo feature for X")
8
add_feature_info(Bar ENABLE_BAR "The bar feature for Y")
9
add_feature_info(Baz ENABLE_BAZ "The baz feature for Z")
10

11
feature_summary(WHAT ALL)

1
# 단일 설정 생성기(Make, Ninja)에서만 유효
2
if(NOT CMAKE_BUILD_TYPE AND NOT CMAKE_CONFIGURATION_TYPES)
3
    message(STATUS "Setting build type to 'Release' as none was specified.")
4
    set(CMAKE_BUILD_TYPE Release CACHE STRING "Choose the type of build." FORCE)
5

6
    # GUI에서 선택 가능한 값 설정
7
    set_property(CACHE CMAKE_BUILD_TYPE PROPERTY STRINGS
8
        "Debug" "Release" "MinSizeRel" "RelWithDebInfo"
9
    )
10
endif()

1
if(CMAKE_BUILD_TYPE STREQUAL "Debug")
2
    target_compile_options(myapp PRIVATE -fsanitize=address)
3
    target_link_options(myapp PRIVATE -fsanitize=address)
4
endif()

1
target_compile_options(myapp PRIVATE
2
    $<$<CONFIG:Debug>:-fsanitize=address,undefined>
3
)
4
target_link_options(myapp PRIVATE
5
    $<$<CONFIG:Debug>:-fsanitize=address,undefined>
6
)

1
#ifndef CONFIG_H
2
#define CONFIG_H
3

4
#define PROJECT_NAME "@PROJECT_NAME@"
5
#define VERSION_MAJOR @PROJECT_VERSION_MAJOR@
6
#define VERSION_MINOR @PROJECT_VERSION_MINOR@
7
#define VERSION_PATCH @PROJECT_VERSION_PATCH@
8

9
#cmakedefine ENABLE_FEATURE_X
10
#cmakedefine01 ENABLE_FEATURE_Y
11

12
#endif

1
set(ENABLE_FEATURE_X ON)
2
set(ENABLE_FEATURE_Y OFF)
3

4
configure_file(
5
    ${CMAKE_CURRENT_SOURCE_DIR}/config.h.in
6
    ${CMAKE_CURRENT_BINARY_DIR}/config.h
7
)
8

9
target_include_directories(myapp PRIVATE ${CMAKE_CURRENT_BINARY_DIR})

1
#ifndef CONFIG_H
2
#define CONFIG_H
3

4
#define PROJECT_NAME "MyApp"
5
#define VERSION_MAJOR 1
6
#define VERSION_MINOR 0
7
#define VERSION_PATCH 0
8

9
#define ENABLE_FEATURE_X
10
/* #undef ENABLE_FEATURE_Y */
11

12
#endif

1
configure_file(
2
    script.sh.in
3
    script.sh
4
    @ONLY    # ${} 형태는 그대로 두고, @...@만 치환
5
)

1
# configure_file() — 한 번만 결정
2
configure_file(version.h.in version.h)
3

4
# file(GENERATE) — 각 구성마다 결정 (예: pkg-config 파일)
5
file(GENERATE
6
    OUTPUT mylib-$<CONFIG>.pc
7
    INPUT mylib.pc.in
8
)

1
{
2
    "version": 6,
3
    "configurePresets": [
4
        {
5
            "name": "debug",
6
            "displayName": "Debug Build",
7
            "generator": "Ninja",
8
            "binaryDir": "${sourceDir}/build/debug",
9
            "cacheVariables": {
10
                "CMAKE_BUILD_TYPE": "Debug",
11
                "ENABLE_TESTING": "ON",
12
                "ENABLE_SANITIZERS": "ON"
13
            }
14
        },
15
        {
16
            "name": "release",
17
            "displayName": "Release Build",
18
            "generator": "Ninja",
19
            "binaryDir": "${sourceDir}/build/release",
20
            "cacheVariables": {
21
                "CMAKE_BUILD_TYPE": "Release",
22
                "ENABLE_TESTING": "OFF"
23
            }
24
        }
25
    ],
26
    "buildPresets": [
27
        {
28
            "name": "debug",
29
            "configurePreset": "debug"
30
        },
31
        {
32
            "name": "release",
33
            "configurePreset": "release"
34
        }
35
    ]
36
}

1
{
2
    "version": 6,
3
    "configurePresets": [
4
        {
5
            "name": "base",
6
            "hidden": true,
7
            "generator": "Ninja",
8
            "cacheVariables": {
9
                "CMAKE_CXX_STANDARD": "17"
10
            }
11
        },
12
        {
13
            "name": "debug",
14
            "inherits": "base",
15
            "binaryDir": "${sourceDir}/build/debug",
16
            "cacheVariables": {
17
                "CMAKE_BUILD_TYPE": "Debug"
18
            }
19
        },
20
        {
21
            "name": "release",
22
            "inherits": "base",
23
            "binaryDir": "${sourceDir}/build/release",
24
            "cacheVariables": {
25
                "CMAKE_BUILD_TYPE": "Release"
26
            }
27
        }
28
    ]
29
}

1
cmake_minimum_required(VERSION 3.15)
2
project(MyApp VERSION 1.0.0 LANGUAGES CXX)
3

4
# === 옵션 ===
5
option(BUILD_SHARED_LIBS "Build shared libraries" OFF)
6
option(ENABLE_TESTING "Enable unit tests" ON)
7
option(ENABLE_COVERAGE "Enable code coverage" OFF)
8
option(ENABLE_SANITIZERS "Enable sanitizers in Debug" ON)
9
option(USE_SYSTEM_JSON "Use system nlohmann_json" OFF)
10

11
include(CMakeDependentOption)
12
cmake_dependent_option(
13
    ENABLE_COVERAGE_HTML "Generate HTML coverage report" ON
14
    "ENABLE_COVERAGE" OFF
15
)
16

17
# === 빌드 타입 기본값 ===
18
if(NOT CMAKE_BUILD_TYPE AND NOT CMAKE_CONFIGURATION_TYPES)
19
    message(STATUS "Setting build type to 'Release'")
20
    set(CMAKE_BUILD_TYPE Release CACHE STRING "" FORCE)
21
    set_property(CACHE CMAKE_BUILD_TYPE PROPERTY STRINGS
22
        Debug Release MinSizeRel RelWithDebInfo
23
    )
24
endif()
25

26
# === 설정 헤더 생성 ===
27
configure_file(config.h.in config.h)
28

29
# === 컴파일러 설정 ===
30
set(CMAKE_CXX_STANDARD 17)
31
set(CMAKE_CXX_STANDARD_REQUIRED ON)
32
set(CMAKE_CXX_EXTENSIONS OFF)
33

34
# === 라이브러리 ===
35
add_library(mylib src/mylib.cpp)
36
target_include_directories(mylib
37
    PUBLIC include
38
    PRIVATE ${CMAKE_CURRENT_BINARY_DIR}
39
)
40

41
# === 실행 파일 ===
42
add_executable(myapp src/main.cpp)
43
target_link_libraries(myapp PRIVATE mylib)
44

45
# === Sanitizers ===
46
if(ENABLE_SANITIZERS)
47
    target_compile_options(mylib PRIVATE
48
        $<$<CONFIG:Debug>:-fsanitize=address,undefined>
49
    )
50
    target_link_options(mylib PRIVATE
51
        $<$<CONFIG:Debug>:-fsanitize=address,undefined>
52
    )
53
endif()
54

55
# === 테스트 ===
56
if(ENABLE_TESTING)
57
    enable_testing()
58
    add_subdirectory(tests)
59
endif()
60

61
# === 요약 출력 ===
62
include(FeatureSummary)
63
add_feature_info(Testing ENABLE_TESTING "Unit tests")
64
add_feature_info(Coverage ENABLE_COVERAGE "Code coverage")
65
add_feature_info(Sanitizers ENABLE_SANITIZERS "Address/UB sanitizers")
66
add_feature_info(SystemJSON USE_SYSTEM_JSON "System nlohmann_json")
67
feature_summary(WHAT ALL)

1
# 회피: 캐시에 이미 있으면 기본값 무시됨
2
cmake -B build -DENABLE_TESTS=OFF  # 처음 실행
3
# ... 나중에 CMakeLists.txt 수정 ...
4
option(ENABLE_TESTS "..." ON)  # 기본값 ON으로 변경
5
cmake -B build  # 여전히 OFF (캐시에 남아 있음)
6

7
# 해결: 명시적으로 변경하거나 캐시 삭제
8
cmake -B build -DENABLE_TESTS=ON  # 명시적 설정
9
# 또는
10
rm build/CMakeCache.txt && cmake -B build

1
# 회피: Visual Studio에서 CMAKE_BUILD_TYPE은 빈 문자열
2
if(CMAKE_BUILD_TYPE STREQUAL "Debug")
3
    target_compile_definitions(app PRIVATE DEBUG_MODE)
4
endif()
5
# Visual Studio에서는 항상 거짓
6

7
# Good: 제너레이터 표현식 사용
8
target_compile_definitions(app PRIVATE
9
    $<$<CONFIG:Debug>:DEBUG_MODE>
10
)

1
# 회피: 사용자 설정을 무시함
2
option(ENABLE_TESTS "..." ON)
3
# 사용자가 cmake -DENABLE_TESTS=OFF 로 실행해도...
4
set(ENABLE_TESTS ON CACHE BOOL "" FORCE)  # 강제로 ON
5
# 사용자가 혼란스러움
6

7
# Good: FORCE는 계산된 값에만 사용
8
set(DETECTED_INCLUDE_PATH "${FOUND_PATH}/include" CACHE PATH "" FORCE)

1
# 회피: 일반 변수 설정이 캐시에 반영 안 됨
2
set(ENABLE_TESTS OFF)  # 일반 변수
3
# 캐시의 ENABLE_TESTS는 여전히 이전 값
4

5
# Good: 캐시 변수 사용
6
set(ENABLE_TESTS OFF CACHE BOOL "" FORCE)
7
# 또는 명령줄에서
8
# cmake -B build -DENABLE_TESTS=OFF