我试图使用CMake构建一个使用JSONCpp的项目。我想下载JSONCpp,在本地编译并链接到它。项目结构在单独的位置具有第三方目录的CMake文件。我收到两个错误。
有谁知道如何关闭全局安装的尝试?如何以可移植的方式将链接器指向正确的位置?
我使用的项目结构是:
./jsoncpp_build_test.cc
./third_party/CMakeLists.txt.jsoncpp
./third_party/CMakeLists.txt
./CMakeLists.txt
源文件jsoncpp_build_test
是:
#include <iostream>
#include "json/json.h"
int main(int argc, char **argv) {
Json::Value json_doc;
std::cout << json_doc.asString() << std::endl;
return 0;
}
主./CMakeLists.txt
文件。
project(jsontest CXX C)
cmake_minimum_required(VERSION 2.8.12)
add_subdirectory(third_party)
set(jsoncpp_lib_dir ${CMAKE_BINARY_DIR}/jsoncpp-build/src/lib_json)
set(jsoncpp_src_dir ${CMAKE_BINARY_DIR}/jsoncpp-src/include)
add_executable(jsoncpp_build_test "jsoncpp_build_test.cc")
target_include_directories(jsoncpp_build_test PRIVATE ${jsoncpp_src_dir})
target_include_directories(jsoncpp_build_test PRIVATE ${jsoncpp_lib_dir})
target_link_libraries(jsoncpp_build_test jsoncpp)
third_party/CMakeLists.txt
文件。我试图下载JSONCpp并安装它以避免用户必须运行多个与构建相关的命令。
configure_file(CMakeLists.txt.jsoncpp
jsoncpp/CMakeLists.txt)
set(jsoncpp_work_dir "${CMAKE_BINARY_DIR}/third_party/jsoncpp")
set(jsoncpp_build_dir "${CMAKE_BINARY_DIR}/jsoncpp-build")
set(jsoncpp_lib_dir "${CMAKE_BINARY_DIR}/jsoncpp-lib")
execute_process(COMMAND ${CMAKE_COMMAND} -G "${CMAKE_GENERATOR}" .
WORKING_DIRECTORY ${jsoncpp_work_dir} )
message(STATUS "INSTALL DIR is ${CMAKE_INSTALL_PREFIX}")
set(CMAKE_INSTALL_COMPONENT "${CMAKE_BINARY_DIR}/jsoncpp-lib")
message(STATUS "INSTALL COMPONENT is ${CMAKE_INSTALL_COMPONENT}")
execute_process(COMMAND ${CMAKE_COMMAND} --build .
WORKING_DIRECTORY ${jsoncpp_work_dir} )
最后,使用ExternalProject_Add模块的third_party/CMakeLists.txt.json
文件。
cmake_minimum_required(VERSION 2.8.12)
project(jsoncpp-download NONE)
set(jsoncpp_install_prefix "${CMAKE_BINARY_DIR}/jsoncpp-lib")
set(CMAKE_INSTALL_COMPONENT "${jsoncpp_install_prefix}")
include(ExternalProject)
ExternalProject_Add(jsoncpp-parser
GIT_REPOSITORY https://github.com/open-source-parsers/jsoncpp.git
GIT_TAG master
SOURCE_DIR "${CMAKE_BINARY_DIR}/jsoncpp-src"
BINARY_DIR "${CMAKE_BINARY_DIR}/jsoncpp-build"
INSTALL_DIR "${CMAKE_BINARY_DIR}/jsoncpp-lib"
CMAKE_ARGS "-DCMAKE_INSTALL_PREFIX=${jsoncpp_install_prefix}"
)
cd build && cmake ../
的结果如下。我不想在全球范围内安装jsoncpp。
-- The CXX compiler identification is GNU 4.8.4
-- The C compiler identification is GNU 4.8.4
...
[100%] Built target jsoncpp_test
[ 87%] Performing install step for 'jsoncpp-parser'
[ 50%] Built target jsoncpp_lib_static
[ 66%] Built target jsontestrunner_exe
[100%] Built target jsoncpp_test
Install the project...
-- Install configuration: "Release"
CMake Error at cmake_install.cmake:44 (FILE):
file cannot create directory: /lib/pkgconfig. Maybe need administrative privileges.
make[3]: *** [install] Error 1
make[2]: *** [jsoncpp-parser-prefix/src/jsoncpp-parser-stamp/jsoncpp-parser-install] Error 2
make[1]: *** [CMakeFiles/jsoncpp-parser.dir/all] Error 2
make: *** [all] Error 2
-- Configuring done
-- Generating done
-- Build files have been written to: /tmp/cmake_test/build
make
的结果是:
Scanning dependencies of target jsoncpp_build_test
[100%] Building CXX object
CMakeFiles/jsoncpp_build_test.dir/jsoncpp_build_test.cc.o
Linking CXX executable jsoncpp_build_test
/usr/bin/ld: cannot find -ljsoncpp
collect2: error: ld returned 1 exit status
make[2]: *** [jsoncpp_build_test] Error 1
make[1]: *** [CMakeFiles/jsoncpp_build_test.dir/all] Error 2
make: *** [all] Error 2
答案 0 :(得分:1)
默认情况下,命令configure_file
将所有出现的${var_name}
替换为对应变量的值。
所以它用空字符串替换${jsoncpp_install_prefix}
,因为调用者的上下文中没有 jsoncpp_install_prefix 变量
如果您只想替换某些变量的引用,可以使用该命令的@ONLY
选项,这样只会替换@var_name@
次出现,但${var_name}
仍将保留不变:
<强> THIRD_PARTY / CMakeLists.txt.json 强>:
cmake_minimum_required(VERSION 2.8.12)
project(jsoncpp-download NONE)
# This reference will be replaced when configured
set(jsoncpp_install_prefix "@CMAKE_BINARY_DIR@/jsoncpp-lib")
# But this reference remains unchanged, until resulted CMakeLists.txt will be interpreted.
set(CMAKE_INSTALL_COMPONENT "${jsoncpp_install_prefix}")
...
<强> THIRD_PARTY /的CMakeLists.txt 强>:
configure_file(CMakeLists.txt.json
jsoncpp/CMakeLists.txt
@ONLY)