[kbuild-all] arch/x86/purgatory/purgatory.c:76:6: warning: no previous prototype for 'warn'

tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master head: dd0d718152e4c65b173070d48ea9dfc06894c3e5 commit: b059f801a937d164e03b33c1848bb3dca67c0b04 x86/purgatory: Use CFLAGS_REMOVE rather than reset KBUILD_CFLAGS date: 11 months ago config: x86_64-randconfig-r015-20200623 (attached as .config) compiler: gcc-5 (Ubuntu 5.5.0-12ubuntu1) 5.5.0 20171010 reproduce (this is a W=1 build): git checkout b059f801a937d164e03b33c1848bb3dca67c0b04 # save the attached .config to linux build tree make W=1 ARCH=x86_64 If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp(a)intel.com&gt; All warnings (new ones prefixed by >>): void warn(const char *msg) {} ^ -- In file included from arch/x86/boot/compressed/string.c:11:0: int bcmp(const void *s1, const void *s2, size_t len) ^ long simple_strtol(const char *cp, char **endp, unsigned int base) ^ void *memmove(void *dest, const void *src, size_t n) ^ vim +/warn +76 arch/x86/purgatory/purgatory.c 4ce97317f41d385 Nick Desaulniers 2019-08-07 71 4ce97317f41d385 Nick Desaulniers 2019-08-07 72 /* 4ce97317f41d385 Nick Desaulniers 2019-08-07 73 * Defined in order to reuse memcpy() and memset() from 4ce97317f41d385 Nick Desaulniers 2019-08-07 74 * arch/x86/boot/compressed/string.c 4ce97317f41d385 Nick Desaulniers 2019-08-07 75 */ 4ce97317f41d385 Nick Desaulniers 2019-08-07 @76 void warn(const char *msg) {} :::::: The code at line 76 was first introduced by commit :::::: 4ce97317f41d38584fb93578e922fcd19e535f5b x86/purgatory: Do not use __builtin_memcpy and __builtin_memset :::::: TO: Nick Desaulniers <ndesaulniers(a)google.com&gt; :::::: CC: Thomas Gleixner <tglx(a)linutronix.de&gt; --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org