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/nathan/linux.git/commit/?id=5aa3e312a14a904fe3a91d3e0366007253c52de4
        git remote add nathan https://git.kernel.org/pub/scm/linux/kernel/git/nathan/linux.git
        git fetch --no-tags nathan b4/llvm-trap-unreachable
        git checkout 5aa3e312a14a904fe3a91d3e0366007253c52de4
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-19 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=x86_64 olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-19 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash