error: unrecognized command line option '-Wshorten-64-to-32' error: command '/usr/local/bin/gcc-5' failed with exit status 1

OS: macos mojave
$ which gcc-5
output: /usr/local/bin/gcc-5

$python setup.py build_ext --inplace
Error:  error: unrecognized command line option '-Wshorten-64-to-32' error: command 
           '/usr/local/bin/gcc-5' failed with exit status 1
