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How to compile jsoncpp with -fPIC through cmake

I want to compile jsoncpp with -fPIC through cmake.

In the website for jsoncpp, it is explaining the way normally to compile like below.

mkdir -p build/debug
cd build/debug
cmake -DCMAKE_BUILD_TYPE=debug -DJSONCPP_LIB_BUILD_STATIC=ON -DJSONCPP_LIB_BUILD_SHARED=OFF -G "Unix Makefiles" ../..
make

How can i compile with -fPIC flag in this step?

---------------------------------------------------------Edit-----------------------------------------------------------

I assume i have to put some line in makefile for -fPIC.

So i add the content of makefile by cmake.

how can i change this makefile for -fPIC flag?

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Solution

  • You have to change the CMAKE_CXX_FLAGS and the CMAKE_C_FLAGS variable. You can do that via the ccmake or cmake-gui (you'll have to toggle advanced) or you can provide it as you were doing:

    cmake -DCMAKE_CXX_FLAGS=-fPIC -DCMAKE_C_FLAGS=-fPIC -DCMAKE_BUILD_TYPE=debug -DJSONCPP_LIB_BUILD_STATIC=ON -DJSONCPP_LIB_BUILD_SHARED=OFF -G "Unix Makefiles" ../..

    Don't bother changing the Makefile, as it would be overwritten the next time you ran cmake.

    In CMake 2.8.9 you can set the POSITION_INDEPENDENT_CODE property on a target to make all following targets position independent. Or you can set the global variable within the CMakeLists.txt

    set(CMAKE_POSITION_INDEPENDENT_CODE ON)

    or

    cmake -DCMAKE_POSITION_INDEPENDENT_CODE=ON ..