使用 cmake 中的自动工具构建库

Question

这是我第一次尝试使用 cmake，如果可能的话，我希望得到一些关于我所做的事情的反馈，因为仍然存在一些问题。

在库文件夹的 CMakeLists.txt 中，我创建了两个 makefile 目标：configure-antlr3c 和 antlr3c。第一个目标运行 autotools 配置 shell 脚本，第二个目标运行 make 可执行文件来构建库：

# CMakeLists.txt in libantlr3c-3.1.3 
add_custom_target(
  configure-antlr3c
  ${SHELL_EXECUTABLE} configure
  WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}
)

add_custom_target(
  antlr3c
   ${MAKE}
   DEPENDS configure-antlr3c
   WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}
)

主要问题是 configure-antlr3c 目标始终“过时”，因此它始终会即使没有发生任何变化也会被执行。此外，我必须在单独的目录（而不是在我的项目的根目录中）生成我的cmake makefile，以避免覆盖库的autotools Makefile...

有人遇到过这个问题吗（使用cmake构建autotools项目）？如果是这样，您的解决方案是什么？

谢谢。

编辑：解决方案 在根 CMakeLists.txt 中：

include(ExternalProject)
ExternalProject_Add(
  libantlr3c
  SOURCE_DIR ${CMAKE_CURRENT_SOURCE_DIR}/lib/libantlr3c-3.1.3
  CONFIGURE_COMMAND ${CMAKE_CURRENT_SOURCE_DIR}/lib/libantlr3c-3.1.3/configure --prefix=${CMAKE_CURRENT_SOURCE_DIR}/lib/libantlr3c-3.1.3
  PREFIX ${CMAKE_CURRENT_SOURCE_DIR}/lib/libantlr3c-3.1.3
  BUILD_COMMAND make
  BUILD_IN_SOURCE 1
)

Answer 1

我认为你最好使用 ExternalProject< /a> cmake 的功能。我猜你有你的项目并且在子目录中有 libantrl ？

project
      +- libantlr
      +- mysrc
  ---- etc ----

如果是这种情况，您可以在顶层 CMakeLists.txt 中执行类似的操作：

cmake_minimum_required(VERSION 2.8)
project(test)
include(ExternalProject)
ExternalProject_Add(libantlr
    SOURCE_DIR ${CMAKE_CURRENT_SOURCE_DIR}/libantlr
    CONFIGURE_COMMAND ${CMAKE_CURRENT_SOURCE_DIR}/libantlr/configure --prefix=<INSTALL_DIR>
    BUILD_COMMAND ${MAKE})

扩展为类似 libantlr-prefix 的内容，因此内容会安装在您的构建树中，而不是在 /usr/local 中，这就是 autotools 在没有前缀的情况下所做的事情。

Answer 2

我在大约四年前发布了下面的答案，似乎仍然偶尔会被点赞。答案“有效”，但在几个方面存在问题。此外，与此同时，CMake 现在拥有 FetchContent，它应该在大多数（如果不是全部）用例中取代 ExternalProject。事实上，任何阅读本文的人都应该考虑使用 CMake Package Manager (CPM)，它包装了FetchContent 并提供了一些非常好的功能，同时与 FetchContent 相比，复杂性相对较小。下面的新示例使用 FetchContent，但可以轻松修改为使用 CPM。

此代码安装 libgpiod，但只需稍加更改即可用于安装使用 autotools 构建的其他软件包。

include(FetchContent)

# This integrates libgpiod into the CMake build process.
# libgpiod uses `autotools`, sometimes referred to as (autohell)[https://www.shlomifish.org/open-source/anti/autohell/].
# While the cmake code below is fairly clean, it was not so easy to discover.
# Here are some notes for things I figured out that may be useful to anyone
# trying to do something similar.
#
# 1. `autotools` typically is used to configure and build in the source directory.
#    This is not ideal for CMake, which prefers to build in a separate directory.
#    The pattern used below does the trick: set the WORKING_DIRECTORY to the
#    binary/build directory, but reference autgen.sh with the source directory path.
# 1b. `autotools` requires packages that we do not typically install in our build
#    images. I had to modify our docker image to include pkg-config & autoconf-archive.
#    The error messages before doing this were not very helpful.
# 2. `FetchContent` is nicer to use than `ExternalProject`. The structure below
#    is similar to how we use `FetchContent` elsewhere.
# 3. `autotools` uses the `CC` and `CXX` environment variables to determine the
#    compiler to use. We want to ensure that when cross-compiling these variables
#    are set to the correct compiler as defined by the toolchain. The code below
#    sets these variables in the environment for the `autogen.sh` script.
# 4. `autotools` uses the `--host` flag to determine the target architecture.
# 5. The INSTALL directory is simply the root of the build directory, e.g.
#    `builds/min-x86` in our build system. In that directory all of the built
#     library and header artifacts are placed into the `lib` and `include`
#     directories, respectively. This is the expected struture for CMake,
#     and we largely get it for free by using `FetchContent`.
# 6. We use `pkg-config` to find the installed library. This is nice but requires
#    that CMAKE_PREFIX_PATH include the INSTALL directory, which bizarrely is
#    not the default.
# 7. `pkg_check_modules` with the `IMPORTED_TARGET` option is able to create
#    a modern cmake target for the library. Such targets are always scoped with
#    `PkgConfig::`. In this case, the target is `PkgConfig::gpiod`.

set(INSTALL ${PROJECT_BINARY_DIR})

list(APPEND CMAKE_PREFIX_PATH ${INSTALL})
find_package(PkgConfig REQUIRED)

FetchContent_Declare(libgpiod
    GIT_REPOSITORY "https://git.kernel.org/pub/scm/libs/libgpiod/libgpiod.git"
    GIT_TAG v2.0.1
    UPDATE_DISCONNECTED ON
)

# If libgpiod is already installed, we can use pkg-config to find it.
pkg_check_modules(gpiod IMPORTED_TARGET libgpiod)

if(NOT libgpiod_POPULATED AND NOT gpiod_FOUND)
    FetchContent_Populate(libgpiod)

    set(ENV${CC} ${CMAKE_C_COMPILER})
    set(ENV{CXX} ${CMAKE_CXX_COMPILER})

    # Configure
    execute_process(
        OUTPUT_QUIET
        COMMAND ${libgpiod_SOURCE_DIR}/autogen.sh --host=${CMAKE_SYSTEM_PROCESSOR} -enable-tools=yes --enable-bindings-cxx --prefix=${INSTALL}
        WORKING_DIRECTORY ${libgpiod_BINARY_DIR}
    )

    # Build
    execute_process(
        OUTPUT_QUIET
        COMMAND make
        WORKING_DIRECTORY ${libgpiod_BINARY_DIR}
    )

    # Install
    execute_process(
        OUTPUT_QUIET
        COMMAND make install
        WORKING_DIRECTORY ${libgpiod_BINARY_DIR}
    )

    pkg_check_modules(gpiod REQUIRED IMPORTED_TARGET libgpiod)

endif()

---

下面是 4 年前的答案，可能作为参考很有用。

我需要做类似的事情，但发现很难找到可行的解决方案，尽管这里提供了示例并提供了已接受的答案，以及其他几篇博客文章中提供的代码片段、CMake 支持电子邮件 listserv 档案等。为了让遇到此问题的其他人受益，这里是我的解决方案。

我们想要使用的外部项目是 libmodbus，尽管我相信我的解决方案足够通用，可以与使用 ./autoconf 的标准 autoconf 配方配置的任何项目一起使用.sh &&配置.sh &&制作&&进行安装。

我们想要添加 libmodbus 作为 git 存储库的子模块。我们将其添加到存储库的路径 /opt/libmodbus 中。配置它的 CMake 代码位于 /cmake/modbus.cmake 中，它包含在我们的根 CMakeLists.txt 中使用

# libmodbus
include(cmake/modbus.cmake)

cmake/modbus.cmake 的内容是：

include(ExternalProject)

set(MODBUS_DIR ${CMAKE_CURRENT_SOURCE_DIR}/opt/libmodbus)
set(MODBUS_BIN ${CMAKE_CURRENT_BINARY_DIR}/libmodbus)
set(MODBUS_STATIC_LIB ${MODBUS_BIN}/lib/libmodbus.a)
set(MODBUS_INCLUDES ${MODBUS_BIN}/include)

file(MAKE_DIRECTORY ${MODBUS_INCLUDES})

ExternalProject_Add(
    libmodbus
    PREFIX ${MODBUS_BIN}
    SOURCE_DIR ${MODBUS_DIR}
    DOWNLOAD_COMMAND cd ${MODBUS_DIR} && git clean -dfX && ${MODBUS_DIR}/autogen.sh
    CONFIGURE_COMMAND ${MODBUS_DIR}/configure --srcdir=${MODBUS_DIR} --prefix=${MODBUS_BIN} --enable-static=yes --disable-shared
    BUILD_COMMAND make
    INSTALL_COMMAND make install
    BUILD_BYPRODUCTS ${MODBUS_STATIC_LIB}
)

add_library(modbus STATIC IMPORTED GLOBAL)

add_dependencies(modbus libmodbus)

set_target_properties(modbus PROPERTIES IMPORTED_LOCATION ${MODBUS_STATIC_LIB})
set_target_properties(modbus PROPERTIES INTERFACE_INCLUDE_DIRECTORIES ${MODBUS_INCLUDES})

使用 libmodbus 的组件可以照常声明其依赖项：

    add_executable(hello_modbus main.cpp)
    target_link_libraries(hello_modbus modbus)

一些注意事项：

1. 这滥用了 DOWNLOAD_COMMAND代码>执行 autogen.sh 步骤。 git clean -dfX 可能不是必需的（它是使用 BUILD_IN_SOURCE 选项的早期版本的剩余部分。如果您确实想下载代码而不是使用git 子模块，您需要适当地修改此行，
2. ，我们会不厌其烦地强制构建静态库。
3. 如果您想要共享库 如果没有 BUILD_BYPRODUCTS ${MODBUS_STATIC_LIB} 声明，用于设置 IMPORTED_LOCATION 的 set_target_properties 命令将会失败。
4. 同样，set_target_properties 命令 也会失败。如果没有 file(MAKE_DIRECTORY) 设置 INTERFACE_INCLUDE_DIRECTORIES 将失败${MODBUS_INCLUDES})。