如何克隆外部(来自 git)cmake 项目并将其集成到本地项目中

How to clone and integrate external (from git) cmake project into local one(如何克隆外部(来自 git)cmake 项目并将其集成到本地项目中)

问题描述

我在尝试使用 Google Test 时遇到了一个问题.

I faced with a problem when I was trying to use Google Test.

关于如何使用ExternalProject_Add将gtest添加到项目中有很多手册，但其中大部分描述了一种基于使用gtest下载zip存档并构建它的方法.

There are lot of manuals on how to use ExternalProject_Add for the adding gtest into the project, however most of these describe a method based on downloading zip archive with gtest and build it.

众所周知，gtest 是 github 托管和基于 cmake 的项目.所以我想找到原生的 cmake 方式.

As we know gtest is github-hosted and cmake-based project. So I'd like to find native cmake way.

如果这是一个只有头文件的项目，我会这样写:

If this would be a header-only project, I'd write something like:

cmake_minimum_required(VERSION 2.8.8)
include(ExternalProject)
find_package(Git REQUIRED)

ExternalProject_Add(
    gtest
    PREFIX ${CMAKE_CURRENT_SOURCE_DIR}/ext
    GIT_REPOSITORY https://github.com/google/googletest.git
    TIMEOUT 10
    UPDATE_COMMAND ${GIT_EXECUTABLE} pull
    CONFIGURE_COMMAND ""
    BUILD_COMMAND ""
    INSTALL_COMMAND ""
    LOG_DOWNLOAD ON
)

ExternalProject_Get_Property(gtest source_dir)
set(GTEST_INCLUDE_DIR ${source_dir}/googletest/include CACHE INTERNAL "Path to include folder for GTest")
set(GTEST_ROOT_DIR ${source_dir}/googletest CACHE INTERNAL "Path to source folder for GTest")
include_directories(${INCLUDE_DIRECTORIES} ${GTEST_INCLUDE_DIR} ${GTEST_ROOT_DIR})
message(${GTEST_INCLUDE_DIR})

并从我的 cmake 项目中添加此脚本，例如:

and add this script from my cmake project like:

 set(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} "${CMAKE_SOURCE_DIR}/cmake.modules/")
 include(AddGTest)
....
 add_dependencies(${PROJECT_NAME} gtest)

然而，这需要一个构建步骤.

However this requires a build step.

这应该如何实施?

1. 通过将 BUILD_COMMAND 添加到 ExternaProject_Add 并与生成的库链接?
2. 或者将 gtest 的 cmakelists 包含到我的项目中，如下所示:

1. By adding BUILD_COMMAND into ExternaProject_Add and linking with produced libs?
2. Or by including gtest's cmakelists into my project, something like this:

add_subdirectory (${CMAKE_SOURCE_DIR}extsrcgtestgoogletestCMakeLists.txt)

这不是正确的方法，因为在项目加载时文件夹不存在.

this is not correct way because on the moment of the project load the folder does not exist.

1. 还有其他方法吗?

什么是正确/首选的方式?

What is a correct/prefer way?

推荐答案

我会采用第一种方法.您不需要指定构建命令，因为默认使用 cmake.这可能看起来像:

I would go with the first approach. You don't need to specify a build command because cmake is used by default. This could look like:

cmake_minimum_required(VERSION 3.0)
project(GTestProject)

include(ExternalProject)

set(EXTERNAL_INSTALL_LOCATION ${CMAKE_BINARY_DIR}/external)

ExternalProject_Add(googletest
    GIT_REPOSITORY https://github.com/google/googletest
    CMAKE_ARGS -DCMAKE_INSTALL_PREFIX=${EXTERNAL_INSTALL_LOCATION}
)

include_directories(${EXTERNAL_INSTALL_LOCATION}/include)
link_directories(${EXTERNAL_INSTALL_LOCATION}/lib)

add_executable(FirstTest main.cpp)
add_dependencies(FirstTest googletest)
target_link_libraries(FirstTest gtest gtest_main pthread)

我不知道这是否是正确/首选的方式，如果有的话.如果您想实现第二种方法，则必须首先使用 execute_process 下载代码.

I don't know if this is the correct/preferred way if there even is one. If you wanted to implement your second approach you would have to download the code with execute_process first.

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