Question

防止＆＃34;未定义引用...＆＃34;提升错误，我需要在编译器标志的最后添加boost库。因此，在CMakeLists.txt中我设置：

set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11 -pedantic -O0 -Wall -DBOOST_SYSTEM_NO_DEPRECATED -lboost_system -lboost_filesystem")

然而，cmake的详细输出告诉我在我定义的后面附加了额外的标志：

g++ -std=c++11 -pedantic -O0 -Wall -DBOOST_SYSTEM_NO_DEPRECATED -lboost_system -lboost_filesystem  CMakeFiles/My_Project.dir/main.cpp.o  -o My_Project  -L/usr/local/boost_1_60_0/lib

是否可以更改订单？

完整的CMakeLists.txt：

cmake_minimum_required(VERSION 3.4)
project(My_Project)

set(CMAKE_VERBOSE_MAKEFILE ON)

# This is bad but I currently don't have another working solution.
set(BOOSTROOT "/usr/local/boost_1_60_0/")
set(BOOST_ROOT "/usr/local/boost_1_60_0/")

find_package(Boost 1.60.0 COMPONENTS system filesystem REQUIRED)
if(Boost_FOUND)

    message(STATUS "Boost_INCLUDE_DIRS: ${Boost_INCLUDE_DIRS}")
    message(STATUS "Boost_LIBRARIES: ${Boost_LIBRARIES}")
    message(STATUS "Boost_VERSION: ${Boost_VERSION}")

    link_directories(${Boost_LIBRARY_DIRS})
    include_directories(${Boost_INCLUDE_DIRS})

endif()

add_executable(BoostTest main.cpp)

if(Boost_FOUND)

    target_link_libraries(BoostTest ${Boost_LIBRARIES})

endif()

# Boost libraries appended at the end. However, cmake generates flags like this:
# c++ -std=c++11 -pedantic -O0 -Wall -DBOOST_SYSTEM_NO_DEPRECATED -lboost_system -lboost_filesystem  CMakeFiles/My_Project.dir/main.cpp.o  -o My_Project  -L/usr/local/boost_1_60_0/lib
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11 -pedantic -O0 -Wall -DBOOST_SYSTEM_NO_DEPRECATED -lboost_system -lboost_filesystem")
set(SOURCE_FILES main.cpp)
add_executable(My_Project ${SOURCE_FILES})

由于

Answer 1

您应该使用target_link_libraries而不是手动将-lboost指令附加到编译器标志中。

TARGET_LINK_LIBRARIES(My_Project boost)

还应该提到的是，在编译目标文件后，可能会将链接器作为单独的调用调用

更改编译器标志的顺序

1 个答案: