reproduce:
        git clone https://github.com/intel/lkp-tests.git ~/lkp-tests
        # apt-get install sparse
        # sparse version: v0.6.4-52-g1cf3d98c-dirty
        # https://git.kernel.org/pub/scm/linux/kernel/git/geert/renesas-drivers.git/commit/?id=a7e448b5460131be0eab090896030c6259b32375
        git remote add geert-renesas-drivers https://git.kernel.org/pub/scm/linux/kernel/git/geert/renesas-drivers.git
        git fetch --no-tags geert-renesas-drivers topic/renesas-bsp-rebase-v6.1
        git checkout a7e448b5460131be0eab090896030c6259b32375
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-13.2.0 ~/lkp-tests/kbuild/make.cross C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__ -fmax-errors=unlimited -fmax-warnings=unlimited' O=build_dir ARCH=powerpc olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-13.2.0 ~/lkp-tests/kbuild/make.cross C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__ -fmax-errors=unlimited -fmax-warnings=unlimited' O=build_dir ARCH=powerpc SHELL=/bin/bash drivers/net/can/rcar/