如何通過cmake與-fPIC編譯jsoncpp

Question

我想編譯jsoncpp與-fPIC到cmake。

在jsoncpp的網站中，它通常會解釋如下的編譯方式。

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 

如何在此步驟中使用-fPIC標誌進行編譯？

--------------------------------------------- - - - - - - 編輯 - - - - - - - - - - - - - - - - - - - ----------------------

我假設我必須把一些行放在生成文件中-fPIC。

所以我通過cmake添加makefile的內容。

我怎樣才能改變這個生成文件爲-fPIC國旗？

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Answer 1

你必須改變CMAKE_CXX_FLAGS和CMAKE_CXX_FLAGS變量。你可以做到這一點通過ccmake或cmake-gui（你將不得不切換高級），或者你可以將它作爲你在做：

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" ../.. 

不要刻意改變Makefile，因爲它會被覆蓋下一個你跑了cmake。

在CMake 2.8.9中，您可以在目標上設置POSITION_INDEPENDENT_CODE屬性 以使所有跟隨的目標位置獨立。或者你也可以設置內的CMakeLists.txt

set(CMAKE_POSITION_INDEPENDENT_CODE ON) 

或

cmake -DCMAKE_POSITION_INDEPENDENT_CODE=ON ..