How can i install LightGBM? Error about Could not find OpenMP_C in Mac

I am using Mac os and installing Lightgbm

pip uninstall lightgbmgit clone --recursive https://github.com/Microsoft/LightGBM ; cd LightGBMexport CXX=g++-8 CC=gcc-8mkdir build ; cd buildcmake ..make -j4

I can't install gcc@8 , gcc@7 and so on,so I tried brew install gcc and it worked.

But cmake .. is failed. The error message:

Could NOT find OpenMP_C (missing: OpenMP_C_FLAGS OpenMP_C_LIB_NAMES)

error