reproduce (this is a W=1 build):
        # https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core.git/commit/?id=de02bd98ce95437ae810960cbfb9d500b2b5bb46
        git remote add driver-core https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core.git
        git fetch --no-tags driver-core gregkh-rust
        git checkout de02bd98ce95437ae810960cbfb9d500b2b5bb46
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        make W=1 O=build_dir ARCH=x86_64 olddefconfig
        make W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash rustfmtcheck