如何以跨平台的方式使用CMake ExternalProject_Add或替代方案？

Question

我想建立一个已经将CMake作为我项目的CMake条带的一部分的第三方项目.ExternalProject_Add就是出于此目的,但我发现它只能用于特定的生成器,我想在很多平台上轻松工作.

例如,这里是zlib的外部项目添加脚本,它有自己的CMakeLists.txt:

set(USE_PROJECT_CMAKE_MODULE_PATH "-DCMAKE_MODULE_PATH=${MAKE_MODULE_PATH}")
ExternalProject_Add(ZLIB
                    SOURCE_DIR ${CMAKE_SOURCE_DIR}/external/zlib
                    DOWNLOAD_COMMAND ""
                    UPDATE_COMMAND ""
                    CMAKE_ARGS
                       -DCMAKE_INSTALL_PREFIX=<INSTALL_DIR>
                       -DCMAKE_CXX_FLAGS=${CMAKE_CXX_FLAGS}
                       -DCMAKE_C_FLAGS=${CMAKE_C_FLAGS}
                       -DCMAKE_BUILD_TYPE=${CMAKE_BUILD_TYPE}
                       ${USE_PROJECT_CMAKE_MODULE_PATH}
                    INSTALL_COMMAND "")

ExternalProject_Add_Step(ZLIB installInternally
                         COMMAND cd <BINARY_DIR> && make install
                         DEPENDEES install
                         ALWAYS 1)
ExternalProject_Get_Property(ZLIB install_dir)

if(UNIX)
    set(ZLIB_NAME libz)
else(UNIX)
    set(ZLIB_NAME zlib)
endif(UNIX)

add_library(zlib UNKNOWN IMPORTED)
set_property(TARGET zlib PROPERTY IMPORTED_LOCATION ${install_dir}/lib/${ZLIB_NAME}.a)
set(ZLIB_LIBRARIES zlib)
set(ZLIB_LIBRARIES_OPTIONAL ${ZLIB_LIBRARIES})
set(ZLIB_DIR ${install_dir} CACHE INTERNAL "zlib ROOT dir")
set(ZLIB_INCLUDE_DIRS ${install_dir}/include CACHE INTERNAL "zlib include dirs")
set(ZLIB_DEFINES "-msse2 -mfpmath=sse" CACHE INTERNAL "zlib defines")

这个问题是它适用于make,但不适用于Xcode或Visual Studio.也许有一些方法可以将传递给我的项目的cmake构建命令转发给ExternalProject_Add.

如何以最小的代码复杂性以跨平台的方式编写ExternalProject_Add调用,还是有更好的选择？

Answer 1

问题

-DCMAKE_BUILD_TYPE=${CMAKE_BUILD_TYPE}

这对于单配置项目来说已经足够了.但是对于Xcode和Visual Studio,您需要在构建阶段设置CMAKE_CONFIGURATION_TYPESplus调用build . --config.看我的回答.

COMMAND cd <BINARY_DIR> && make install

这当然只适用于Makefile生成器.要跨平台,您可以使用:--build . --target install --configinside INSTALL_COMMANDof ExternalProject_Add.

看一下这个模板文件,特别是以下几行:

ExternalProject_Add(
    "${current_project}"
    URL
    @HUNTER_PACKAGE_URL@
    URL_HASH
    SHA1=@HUNTER_PACKAGE_SHA1@
    DOWNLOAD_DIR
    "@HUNTER_PACKAGE_DOWNLOAD_DIR@"
    SOURCE_DIR
    "@HUNTER_PACKAGE_SOURCE_DIR@"
    INSTALL_DIR
    "@HUNTER_PACKAGE_INSTALL_PREFIX@"
        # Not used, just avoid creating Install/<name> empty directory
    BUILD_COMMAND ""
        # This command is empty because all necessary targets will
        # be built on install stage
    CMAKE_ARGS
    "-G@CMAKE_GENERATOR@"
    "-C@HUNTER_CACHE_FILE@"
    "-C@HUNTER_ARGS_FILE@"
    "-D${postfix_name}=${${postfix_name}}"
    "-DCMAKE_BUILD_TYPE=${configuration}"
    "-DCMAKE_CONFIGURATION_TYPES=${configuration}"
    "-DCMAKE_INSTALL_PREFIX=@HUNTER_PACKAGE_INSTALL_PREFIX@"
    "-DCMAKE_TOOLCHAIN_FILE=${CMAKE_TOOLCHAIN_FILE}"
    INSTALL_COMMAND
        "@CMAKE_COMMAND@"
        --build .
        --target install
        --config ${configuration}
        --
        ${jobs_option}
)

替代

还是有更好的选择？

你见过猎人吗？

您可以像这样添加zlib :

hunter_add_package(ZLIB)
find_package(ZLIB CONFIG REQUIRED)
target_link_libraries(... ZLIB::zlib)

这段代码无处不在.将在配置步骤中自动下载第三方.使用不同的生成器/工具链构建示例(build.py只是设置CMAKE_TOOLCHAIN_FILE和-G/的CMake包装器-B):

build.py --toolchain mingw --config Release # MinGW Makefiles
build.py --toolchain vs-12-2013 --config Debug # Visual Studio 12 2013
build.py --toolchain xcode --config Release # Xcode
build.py --toolchain libcxx --config Release # Makefile with -stdlib=libc++ toolchain
build.py --toolchain ios-8-2 --config Release # Xcode with iOS SDK 8.2 toolchain

在构建第三方软件包时,您可以完全控制您希望拥有的选项,构建类型或作业数量.例如,您可以为zlib构建4种类型的Debug,Release,MinSizeRel,RelWithDebInfo,并将MinSizeRel链接到当前项目:

> build.py --toolchain xcode --verbose --config MinSizeRel --fwd "HUNTER_CONFIGURATION_TYPES=Release;Debug;MinSizeRel;RelWithDebInfo"
/.../clang  /.../lib/libz-MinSizeRel.a ... -o /.../_builds/xcode/MinSizeRel/foo

> ls -la /.../.hunter/_Base/d1232c0/326318e/37e4682/Install/lib/libz*
   99056 /.../.hunter/_Base/d1232c0/326318e/37e4682/Install/lib/libz-MinSizeRel.a
  307872 /.../.hunter/_Base/d1232c0/326318e/37e4682/Install/lib/libz-RelWithDebInfo.a
  109536 /.../.hunter/_Base/d1232c0/326318e/37e4682/Install/lib/libz.a
  258904 /.../.hunter/_Base/d1232c0/326318e/37e4682/Install/lib/libzd.a