tree: https://git.kernel.org/pub/scm/linux/kernel/git/gustavoars/linux.git for-next/clang-fallthrough head: 58d0d2d2e7dc1b1a4997bb9c47d6cf428f2d3a00 commit: 58d0d2d2e7dc1b1a4997bb9c47d6cf428f2d3a00 [1/1] Revert "Revert "Makefile: Enable -Wimplicit-fallthrough for Clang"" config: hexagon-randconfig-r023-20210804 (attached as .config) compiler: clang version 12.0.0 reproduce (this is a W=1 build): wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross chmod +x ~/bin/make.cross # https://git.kernel.org/pub/scm/linux/kernel/git/gustavoars/linux.git/commit/?id=58d0d2d2e7dc1b1a4997bb9c47d6cf428f2d3a00 git remote add gustavoars-linux https://git.kernel.org/pub/scm/linux/kernel/git/gustavoars/linux.git git fetch --no-tags gustavoars-linux for-next/clang-fallthrough git checkout 58d0d2d2e7dc1b1a4997bb9c47d6cf428f2d3a00 # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=hexagon If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot All warnings (new ones prefixed by >>): >> warning: fallthrough annotation in unreachable code [-Wimplicit-fallthrough] >> warning: fallthrough annotation in unreachable code [-Wimplicit-fallthrough] 2 warnings generated. --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org