reproduce:
        # apt-get install sparse
        # sparse version: v0.6.4-52-g1cf3d98c-dirty
        # https://github.com/zen-kernel/zen-kernel/commit/5d8376057790252b220d3a5eea2b628106f69d38
        git remote add zen https://github.com/zen-kernel/zen-kernel
        git fetch --no-tags zen 6.6/bbr3
        git checkout 5d8376057790252b220d3a5eea2b628106f69d38
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        make W=1 C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__ -fmax-errors=unlimited -fmax-warnings=unlimited' O=build_dir ARCH=i386 olddefconfig
        make W=1 C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__ -fmax-errors=unlimited -fmax-warnings=unlimited' O=build_dir ARCH=i386 SHELL=/bin/bash