reproduce (this is a W=1 build):
        git clone https://github.com/intel/lkp-tests.git ~/lkp-tests
        git remote add abelloni https://git.kernel.org/pub/scm/linux/kernel/git/abelloni/linux.git
        git fetch abelloni rtc-next
        git checkout abelloni/rtc-next
        b4 shazam https://lore.kernel.org/r/694706ad8577a36ef8948e0d9ca7ea561900fbc2.1756908788.git.akhilesh@ee.iitb.ac.in
        # 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