Question

我有一个外部项目，需要构建几个命令：

ExternalProject_Add(
    xmlrpc_build
    PREFIX ${XMLRPC_ROOT}
    SOURCE_DIR ${XMLRPC_ROOT}
    BUILD_IN_SOURCE 1
    CONFIGURE_COMMAND ""
    BUILD_COMMAND ./configure --enable-curl-client CURL_CONFIG=${CURL_CONFIG} COMMAND export CFLAGS=`${CURL_CONFIG} --cflags` COMMAND make -j8
    INSTALL_COMMAND ""
)

不幸的是，cmake逃脱了`，所以命令格式不正确：

export "CFLAGS=\`/xxx/curl-config" "--cflags\`"

我累了把它放进＆＃34;＆＃34;，但没有运气：

BUILD_COMMAND ./configure --enable-curl-client CURL_CONFIG=${CURL_CONFIG} COMMAND "export CFLAGS=`${CURL_CONFIG} --cflags`" COMMAND make -j8

export "CFLAGS=\`/xxx/curl-config" "--cflags\`"

使用$（）而不是“不要帮助”的组合：

BUILD_COMMAND ./configure --enable-curl-client CURL_CONFIG=${CURL_CONFIG} COMMAND "export CFLAGS=$(${CURL_CONFIG} --cflags)" COMMAND make -j8
"export CFLAGS=\$(/xxx/curl-config --cflags)"

BUILD_COMMAND ./configure --enable-curl-client CURL_CONFIG=${CURL_CONFIG} COMMAND export CFLAGS=$(${CURL_CONFIG} --cflags) COMMAND make -j8
export "CFLAGS=\$" "(" /xxx/curl-config --cflags ")"

有没有办法从子流程中获取结果并将其分配给变量？

编辑：从另一个问题尝试解决方案但仍然没有运气：

set(blah "`${CURL_CONFIG} --cflags`")
BUILD_COMMAND ./configure --enable-curl-client CURL_CONFIG=${CURL_CONFIG} COMMAND export CFLAGS=${blah} COMMAND make -j8

export "CFLAGS=\`/xxx/curl-config --cflags\`"

或：

BUILD_COMMAND ./configure --enable-curl-client CURL_CONFIG=${CURL_CONFIG} COMMAND [=[export CFLAGS=`${CURL_CONFIG} --cflags`]=] COMMAND make -j8

"export CFLAGS=\`\${CURL_CONFIG} --cflags\`"

Answer 1

为什么不预先调用它来代替${CURL_CONFIG} --cflags内联External_Project_Add()命令？

find_program(CURL_CONFIG curl-config)
execute_process(COMMAND ${CURL_CONFIG} --cflags
                OUTPUT_VARIABLE CURL_CONFIG_CFLAGS)
ExternalProject_Add(
    xmlrpc_build
    PREFIX ${XMLRPC_ROOT}
    SOURCE_DIR ${XMLRPC_ROOT}
    BUILD_IN_SOURCE 1
    CONFIGURE_COMMAND CFLAGS="${CURL_CONFIG_CFLAGS}" ./configure --enable-curl-client CURL_CONFIG=${CURL_CONFIG}
    BUILD_COMMAND CFLAGS="${CURL_CONFIG_CFLAGS}" make -j8
    INSTALL_COMMAND ""
)

Answer 2

通过一个糟糕的解决方法让它工作（如果没有黑客，这样的琐事是不可能的）：

add_custom_target(
    xmlrpc_build_curl_config
    COMMAND echo -n CFLAGS= > curl_cflags COMMAND ${CURL_CONFIG} --cflags >> curl_cflags
    DEPENDS curl
    WORKING_DIRECTORY "${XMLRPC_ROOT}"
    VERBATIM
)

ExternalProject_Add(
    xmlrpc_build
    PREFIX ${XMLRPC_ROOT}
    SOURCE_DIR ${XMLRPC_ROOT}
    BUILD_IN_SOURCE 1
    CONFIGURE_COMMAND ""
    BUILD_COMMAND ./configure --enable-curl-client CURL_CONFIG=${CURL_CONFIG} COMMAND cat curl_cflags | xargs env COMMAND make -j8
    INSTALL_COMMAND ""
)

add_dependencies(xmlrpc_build xmlrpc_build_curl_config)

在cmake中执行子进程

2 个答案: