c++ - 如何通过cmake使用-fPIC编译jsoncpp

Question

我想通过cmake用-fPIC编译jsoncpp。

在jsoncpp的网站上，是这样解释正常编译的方式。

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

如何在此步骤中使用 -fPIC 标志进行编译？

-------------------------------------------- - - - - - - -编辑 - - - - - - - - - - - - - - - - - - ----------------------

我假设我必须在 makefile 中为 -fPIC 添加一些行。

所以我通过cmake添加了makefile的内容。

我如何更改此 makefile 的 -fPIC 标志？

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Answer 1

您必须更改 CMAKE_CXX_FLAGS 和 CMAKE_C_FLAGS 变量。您可以通过 ccmake 或 cmake-gui 执行此操作(您必须切换为高级)，或者您可以按原样提供它:

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" ../..

不要费心更改 Makefile，因为它会在您下次运行 cmake 时被覆盖。

在 CMake 2.8.9 中，您可以设置 POSITION_INDEPENDENT_CODE 属性 在目标上使所有后续目标位置独立。或者您可以在 CMakeLists.txt

中设置全局变量

set(CMAKE_POSITION_INDEPENDENT_CODE ON)

或

cmake -DCMAKE_POSITION_INDEPENDENT_CODE=ON ..