reproduce (this is a W=1 build):
        git clone https://github.com/intel/lkp-tests.git ~/lkp-tests
        # https://git.kernel.org/pub/scm/linux/kernel/git/arnd/playground.git/commit/?id=c0a2b3cd5b78ddb721e53baf675d7164a118bc2d
        git remote add arnd-playground https://git.kernel.org/pub/scm/linux/kernel/git/arnd/playground.git
        git fetch --no-tags arnd-playground to_build
        git checkout c0a2b3cd5b78ddb721e53baf675d7164a118bc2d
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-20 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=x86_64 olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-20 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash drivers/net/wireless/ath/ath9k/