CMake中project的使用

      CMake中的命令project用于设置项目(project)的名称。其格式如下

project( [...])
project(
        [VERSION [.[.[.]]]]
        [DESCRIPTION ]
        [HOMEPAGE_URL ]
        [LANGUAGES ...])

      设置project的名称，并将其存储在变量PROJECT_NAME中。从顶层(top-level)CMakeLists.txt调用时，还将project名称存储在变量CMAKE_PROJECT_NAME中。
      还设置变量：
      (1).PROJECT_SOURCE_DIR, _SOURCE_DIR: project源目录的绝对路径。
      (2).PROJECT_BINARY_DIR, _BINARY_DIR: project二进制目录的绝对路径。
      (3).PROJECT_IS_TOP_LEVEL, _IS_TOP_LEVEL: 3.21版本中引入，布尔值，指示project是否为top-level。

project(test_cmake)
message("project name: ${PROJECT_NAME}") # project name: test_cmake
message("cmake project name: ${CMAKE_PROJECT_NAME}") # cmake project name: test_cmake

message("project source dir: ${PROJECT_SOURCE_DIR}") # project source dir: /home/spring/GitHub/Linux_Code_Test/Samples_CMake/messy_usage
message("project name source dir: ${${PROJECT_NAME}_SOURCE_DIR}") # project name source dir: /home/spring/GitHub/Linux_Code_Test/Samples_CMake/messy_usage

message("project binary dir: ${PROJECT_BINARY_DIR}") # project binary dir: /home/spring/GitHub/Linux_Code_Test/Samples_CMake/messy_usage/build
message("project name binary dir: ${${PROJECT_NAME}_BINARY_DIR}") # project name binary dir: /home/spring/GitHub/Linux_Code_Test/Samples_CMake/messy_usage/build

message("project is top level: ${PROJECT_IS_TOP_LEVEL}") # project is top level: ON
message("project name is top level: ${${PROJECT_NAME}_IS_TOP_LEVEL}") # project name is top level: ON

      更多的变量由下面描述的可选参数来设置，如果没有使用这些可选参数中的任何一个，则将相应的变量设置为空字符串：
      (1).VERSION :除非policy CMP0048设置为NEW，否则不能使用。采用由非负整数组成的参数，即[.[.[.]]],并设置变量：

PROJECT_VERSION, _VERSION
PROJECT_VERSION_MAJOR, _VERSION_MAJOR
PROJECT_VERSION_MINOR, _VERSION_MINOR
PROJECT_VERSION_PATCH, _VERSION_PATCH
PROJECT_VERSION_TWEAK, _VERSION_TWEAK

      3.12版本中引入，从顶层(top-level)CMakeLists.txt调用project命令时，版本也存储在变量CMAKE_PROJECT_VERSION中。

cmake_policy(GET CMP0048 var) # 3.0
message("var: ${var}") # var: NEW

project(test_cmake VERSION 1.2.3.4)
message("project version: ${PROJECT_VERSION}, ${${PROJECT_NAME}_VERSION}") # project version: 1.2.3.4, 1.2.3.4
message("project version major: ${PROJECT_VERSION_MAJOR}, ${${PROJECT_NAME}_VERSION_MAJOR}") # project version major: 1, 1
message("project version minor: ${PROJECT_VERSION_MINOR}, ${${PROJECT_NAME}_VERSION_MINOR}") # project version minor: 2, 2
message("project version patch: ${PROJECT_VERSION_PATCH}, ${${PROJECT_NAME}_VERSION_PATCH}") # project version patch: 3, 3
message("project version tweak: ${PROJECT_VERSION_TWEAK}, ${${PROJECT_NAME}_VERSION_TWEAK}") # project version tweak: 4, 4
message("cmake project version: ${CMAKE_PROJECT_VERSION}") # cmake project version: 1.2.3.4

      (2).DESCRIPTION :3.9版本中引入，设置变量PROJECT_DESCRIPTION, _DESCRIPTION为。建议：此描述是比较短的字符串，通常不超过几个单词。
      从顶层(top-level)CMakeLists.txt调用project命令时，描述也存储在变量CMAKE_PROJECT_DESCRIPTION中。在3.12版本中，添加了_DESCRIPTION变量。

project(test_cmake DESCRIPTION "this is cmake test")
message("project description: ${PROJECT_DESCRIPTION}, ${${PROJECT_NAME}_DESCRIPTION}") # project description: this is cmake test, this is cmake test
message("cmake project description: ${CMAKE_PROJECT_DESCRIPTION}") # cmake project description: this is cmake test
message("project name description: ${${PROJECT_NAME}_DESCRIPTION}") # project name description: this is cmake test

      (3).HOMEPAGE_URL :3.12版本中引入，设置变量PROJECT_HOMEPAGE_URL, _HOMEPAGE_URL为，它应该是project的规范主页URL。从顶层(top-level)CMakeLists.txt调用project命令时，URL也存储在变量CMAKE_PROJECT_HOMEPAGE_URL中。

project(test_cmake HOMEPAGE_URL "https://blog.csdn.net/fengbingchun/category_783053.html")
message("project homepage url: ${PROJECT_HOMEPAGE_URL}, ${${PROJECT_NAME}_HOMEPAGE_URL}") # project homepage url: https://blog.csdn.net/fengbingchun/category_783053.html, https://blog.csdn.net/fengbingchun/category_783053.html
message("cmake project homepage url: ${CMAKE_PROJECT_HOMEPAGE_URL}") # cmake project homepage url: https://blog.csdn.net/fengbingchun/category_783053.html

      (4).LANGUAGES ...:也可以在没有LANGUAGES关键字的情况下指定第一个短签名(short signature)。选择构建(build)project所需的编程语言。支持的编程语言包括：C, CXX(i.e. C++), CUDA, OBJC(i.e. Objective-C), OBJCXX, Fortran, HIP, ISPC,和ASM。如果没有给出编程语言选项，默认情况下启用C和CXX。指定编程语言为NONE，或使用LANGUAGES关键字但不列出任何语言，则会跳过启用任何语言。

project(test_cmake)
project(test_cmake CXX)
project(test_cmake LANGUAGES)
project(test_cmake LANGUAGES NONE)
project(test_cmake LANGUAGES CXX ASM)

      3.8版本中添加对CUDA支持。3.16版本中添加对OBJC和OBJCXX支持。3.18版本中添加对ISPC支持。如果启用ASM，请将其列在最后，以便CMake可以检查其它编程语言(例如C)的编译器是否也适用于汇编(assembly)。

project(test_cmake1 VERSION 2.3.4.5 DESCRIPTION "test cmake1" HOMEPAGE_URL "https://blog.csdn.net/fengbingchun" LANGUAGES CXX C ASM)
message("cmake project name: ${CMAKE_PROJECT_NAME}") # cmake project name: test_cmake1
message("cmake project version: ${CMAKE_PROJECT_VERSION}") # cmake project version: 2.3.4.5
message("cmake project description: ${CMAKE_PROJECT_DESCRIPTION}") # cmake project description: test cmake1
message("cmake project homepage url: ${CMAKE_PROJECT_HOMEPAGE_URL}") # cmake project homepage url: https://blog.csdn.net/fengbingchun

project(test_cmake2 VERSION 6.7.8.9 DESCRIPTION "test cmake2" HOMEPAGE_URL "https://github.com/fengbingchun" LANGUAGES CXX)
message("cmake project name: ${CMAKE_PROJECT_NAME}") # cmake project name: test_cmake2
message("cmake project version: ${CMAKE_PROJECT_VERSION}") # cmake project version: 6.7.8.9
message("cmake project description: ${CMAKE_PROJECT_DESCRIPTION}") # cmake project description: test cmake2
message("cmake project homepage url: ${CMAKE_PROJECT_HOMEPAGE_URL}") # cmake project homepage url: https://github.com/fengbingchun

      执行上述测试代码需要3个文件：build.sh, CMakeLists.txt, test_project.cmake

     build.sh内容如下：

#! /bin/bash

# supported input parameters(cmake commands)
params=(function macro cmake_parse_arguments \
		find_library find_path find_file find_program find_package \
		cmake_policy cmake_minimum_required project include \
		string)

usage()
{
	echo "Error: $0 needs to have an input parameter"

	echo "supported input parameters:"
	for param in ${params[@]}; do
		echo "  $0 ${param}"
	done

	exit -1
}

if [ $# != 1 ]; then
	usage
fi

flag=0
for param in ${params[@]}; do
	if [ $1 == ${param} ]; then
		flag=1
		break
	fi
done

if [ ${flag} == 0 ]; then
	echo "Error: parameter \"$1\" is not supported"
	usage
	exit -1
fi

if [[ ! -d "build" ]]; then
	mkdir build
	cd build
else
	cd build
fi

echo "==== test $1 ===="
cmake -DTEST_CMAKE_FEATURE=$1 ..

      CMakeLists.txt内容如下：

cmake_minimum_required(VERSION 3.22)
project(cmake_feature_usage)

message("#### current cmake version: ${CMAKE_MAJOR_VERSION}.${CMAKE_MINOR_VERSION}.${CMAKE_PATCH_VERSION}")
include(test_${TEST_CMAKE_FEATURE}.cmake)
message("==== test finish ====")

      test_project.cmake：为上面的所有示例代码

      执行可能的结果如下图所示：

      GitHub：https://github.com/fengbingchun/Linux_Code_Test