更改编译器标志的顺序

Question

为了防止 "undefined reference to..." boost 错误，我需要在编译器标志的最后附加 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")

但是，cmake 的详细输出显示我定义的标志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

是否可以更改顺序？

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})

谢谢

Answer 1

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

TARGET_LINK_LIBRARIES(My_Project boost)

还应该提到的是，链接器可能作为单独的调用被调用在编译目标文件

之后

更改编译器标志的顺序

Change the order of compiler flags

c++

boost

cmake

clion