Hi Rasmus,

I love your patch! Yet something to improve:

[auto build test ERROR on linux/master]
[also build test ERROR on linus/master v6.1 next-20221220]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Rasmus-Villemoes/string-c-test-cmp-for-all-possible-1-character-strings/20221222-220708
patch link:    https://lore.kernel.org/r/20221222140506.1961281-1-linux%40rasmusvillemoes.dk
patch subject: [PATCH] string.c: test *cmp for all possible 1-character strings
config: riscv-randconfig-r042-20221219
compiler: clang version 16.0.0 (https://github.com/llvm/llvm-project 98b13979fb05f3ed288a900deb843e7b27589e58)
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
        # install riscv cross compiling tool for clang build
        # apt-get install binutils-riscv64-linux-gnu
        # https://github.com/intel-lab-lkp/linux/commit/0235c6544a848ef03332c7840c87b356c08a4b1d
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review Rasmus-Villemoes/string-c-test-cmp-for-all-possible-1-character-strings/20221222-220708
        git checkout 0235c6544a848ef03332c7840c87b356c08a4b1d
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=riscv olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=riscv SHELL=/bin/bash

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@intel.com>

All errors (new ones prefixed by >>):

>> ld.lld: error: undefined symbol: __warn_printk
   >>> referenced by ctype.c
   >>>               arch/riscv/purgatory/purgatory.ro:(test_xxxcmp)
   >>> referenced by ctype.c
   >>>               arch/riscv/purgatory/purgatory.ro:(test_xxxcmp)
   >>> referenced by ctype.c
   >>>               arch/riscv/purgatory/purgatory.ro:(test_xxxcmp)

-- 
0-DAY CI Kernel Test Service
https://01.org/lkp