原文地址：https://www.zoucz.com/blog/2021/06/03/7d832a40-9e7e-11ee-a310-a5483b8ffd93/，参与评论

1. 主要关注点梳理

1.1 结构梳理

1.2 相关文档

命令行参数

https://cmake.org/cmake/help/latest/manual/cmake.1.html

构建系统

https://cmake.org/cmake/help/latest/manual/cmake-buildsystem.7.html

编译系统主要由后面的命令方法和变量组合而成

语言选项、交叉编译工具等

2. 指引文档

全量指引文档见：https://cmake.org/cmake/help/latest/index.html

cmake-buildsystem(7)
cmake-commands(7)
cmake-compile-features(7)
cmake-configure-log(7)
cmake-cxxmodules(7)
cmake-developer(7)
cmake-env-variables(7)
cmake-file-api(7)
cmake-generator-expressions(7)
cmake-generators(7)
cmake-language(7)
cmake-modules(7)
cmake-packages(7)
cmake-policies(7)
cmake-presets(7)
cmake-properties(7)
cmake-qt(7)
cmake-server(7)
cmake-toolchains(7)
cmake-variables(7)
cpack-generators(7)

3. 入门教程

官网教程：https://cmake.org/cmake/help/latest/guide/tutorial/index.html

官网教程源码：https://github.com/Kitware/CMake/tree/master/Help/guide/tutorial

入门教程分为

cmake教程 CMake Tutorial
用户交互指南 User Interaction Guide
使用依赖指南 Using Dependencies Guide
导入导出指南 Importing and Exporting Guide
IDE集成指南 IDE Integration Guide

这里我们只关注最常用的 cmake 教程

3.1 basic

# 指定最低 cmake 版本
cmake_minimum_required(VERSION 3.10)
# 指定项目名
project(Tutorial)
# 指定输出可执行文件
add_executable(Tutorial tutorial.cxx)

3.2 库编译链接

1	add_library(<name> [STATIC \| SHARED \| MODULE] [EXCLUDE_FROM_ALL] [<source>...])

下面以静态库为例

静态库 cmakelists.txt

1 2	# 指定代码文件，编译生成静态库 add_library(MathFunctions MathFunctions.cxx mysqrt.cxx)

可执行文件 cmakelists.txt

# 编译时添加子目录编译（若引入三方静态库，这个不需要）
add_subdirectory(MathFunctions)
# 指定代码文件，编译生成可执行文件
add_executable(Tutorial tutorial.cxx)
# 添加依赖的静态库（此处是子项目生成的 libMathFunctions.a 库）
target_link_libraries(Tutorial PUBLIC MathFunctions)
# 添加依赖库的头文件读取路径
target_include_directories(Tutorial PUBLIC
                          "${PROJECT_BINARY_DIR}"
                          "${PROJECT_SOURCE_DIR}/MathFunctions"
                          )

3.3 cmake 编译选项使用

cmake 创建选项

1	option(USE_MYMATH "Use tutorial provided math implementation" ON)

cmake 中判断选项，给编译过程设置宏定义

1
2
3

if (USE_MYMATH)
  target_compile_definitions(MathFunctions PRIVATE "USE_MYMATH")
endif()

代码中使用编译选项宏

#ifdef USE_MYMATH
  #include "mysqrt.h"
#endif
...
#ifdef USE_MYMATH
return detail::mysqrt(x);
#else
return std::sqrt(x);
#endif

编译命令中设置选项

1	cmake ... -DUSE_MYMATH

3.4 requirements

库项目设置

# INTERFACE 指定引用者需要将代码所在目录添加为 include 路径，但是自己不需要
target_include_directories(MathFunctions
                           INTERFACE ${CMAKE_CURRENT_SOURCE_DIR}
                           )

引用项目不再需要设置 include 目录

# 下面的设置不再需要
target_include_directories(Tutorial PUBLIC
                          "${PROJECT_BINARY_DIR}"
                          "${PROJECT_SOURCE_DIR}/MathFunctions"
                          )

3.5 通过 Interface 设置 C++ 规范

默认的设置方法是这样的

1 2	set(CMAKE_CXX_STANDARD 11) set(CMAKE_CXX_STANDARD_REQUIRED True)

干掉这俩选项后

# 定义 tutorial_compiler_flags INTERFACE，并设置编译 features cxx_std_11
add_library(tutorial_compiler_flags INTERFACE)
target_compile_features(tutorial_compiler_flags INTERFACE cxx_std_11)
...
# 设置链接库时，使用 tutorial_compiler_flags 指定c++标准库版本
target_link_libraries(Tutorial PUBLIC MathFunctions tutorial_compiler_flags)
target_link_libraries(SqrtLibrary PUBLIC tutorial_compiler_flags)
target_link_libraries(MathFunctions PUBLIC tutorial_compiler_flags)
...

3.6 测试

https://cmake.org/cmake/help/latest/guide/tutorial/Installing%20and%20Testing.html

# 启用检测能力
enable_testing()

add_test(NAME Runs COMMAND Tutorial 25)

add_test(NAME Usage COMMAND Tutorial)
set_tests_properties(Usage
  PROPERTIES PASS_REGULAR_EXPRESSION "Usage:.*number"
  )

add_test(NAME StandardUse COMMAND Tutorial 4)
set_tests_properties(StandardUse
  PROPERTIES PASS_REGULAR_EXPRESSION "4 is 2"
  )

function(do_test target arg result)
  add_test(NAME Comp${arg} COMMAND ${target} ${arg})
  set_tests_properties(Comp${arg}
    PROPERTIES PASS_REGULAR_EXPRESSION ${result}
    )
endfunction()

# do a bunch of result based tests
do_test(Tutorial 4 "4 is 2")
do_test(Tutorial 9 "9 is 3")
do_test(Tutorial 5 "5 is 2.236")
do_test(Tutorial 7 "7 is 2.645")
do_test(Tutorial 25 "25 is 5")
do_test(Tutorial -25 "-25 is (-nan|nan|0)")
do_test(Tutorial 0.0001 "0.0001 is 0.01")

运行 ctest -N / ctest -VV

3.7 能力检测

在 cmakelists.txt 中

# 开启源码检测能力
include(CheckCXXSourceCompiles)
...
# 定义能力检测代码片段
check_cxx_source_compiles("
  #include <cmath>
  int main() {
    std::log(1.0);
    return 0;
  }
" HAVE_LOG)
check_cxx_source_compiles("
  #include <cmath>
  int main() {
    std::exp(1.0);
    return 0;
  }
" HAVE_EXP)
...
# 根据检测结果设置编译宏
if(HAVE_LOG AND HAVE_EXP)
  target_compile_definitions(SqrtLibrary
                              PRIVATE "HAVE_LOG" "HAVE_EXP"
                              )
endif()

target_link_libraries(MathFunctions PRIVATE SqrtLibrary)
endif()
...
# 代码中根据宏实现不同逻辑
#if defined(HAVE_LOG) && defined(HAVE_EXP)
  double result = std::exp(std::log(x) * 0.5);
  std::cout << "Computing sqrt of " << x << " to be " << result
            << " using log and exp" << std::endl;
#else
  double result = x;

  // do ten iterations
  for (int i = 0; i < 10; ++i) {
    if (result <= 0) {
      result = 0.1;
    }
    double delta = x - (result * result);
    result = result + 0.5 * delta / result;
    std::cout << "Computing sqrt of " << x << " to be " << result << std::endl;
  }
#endif

3.8 设置默认编译动态/静态库

set(CMAKE_ARCHIVE_OUTPUT_DIRECTORY "${PROJECT_BINARY_DIR}")
set(CMAKE_LIBRARY_OUTPUT_DIRECTORY "${PROJECT_BINARY_DIR}")
set(CMAKE_RUNTIME_OUTPUT_DIRECTORY "${PROJECT_BINARY_DIR}")

option(BUILD_SHARED_LIBS "Build using shared libraries" ON)
...
# 开启 PIC 选项
set_target_properties(SqrtLibrary PROPERTIES
                      POSITION_INDEPENDENT_CODE ${BUILD_SHARED_LIBS}
                      )

本文链接：https://www.zoucz.com/blog/2021/06/03/7d832a40-9e7e-11ee-a310-a5483b8ffd93/

☞ 参与评论

cmake 文档和使用指引梳理